Systems, apparatus, and methods for dilution and effective mixing of high-viscosity, long-acting flame retardant liquid concentrates.

Abstract

A system and method are provided for automatically providing ready-to-use (RTU) flame retardant products. A liquid concentrate (LC) flame retardant is mixed with water to form a flame retardant compound. The LC head pressure of the LC flame retardant changes while the LC flame retardant and water are mixed, and the in-line refractive index of the RTU flame retardant product is automatically and repeatedly measured. At least one flow parameter is adjusted or maintained during the mixing process to achieve a target refractive index of the RTU flame retardant product.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 63 / 509,087, filed on June 20, 2023, with the title "Systems, Apparatus, and Methods for Dilution and Effective Mixing of High Viscosity Long - Term Fire Retardant Liquid Concentrates", which is hereby incorporated by reference in its entirety.

Background Art

[0002] Long - term fire retardants contain flame - retardant salts that reduce fire intensity and slow the progression of wildfires. Such fire retardants have conventionally been available as dry powders or liquid concentrates (LCs) that are mixed with water, and the resulting "ready - to - use" (RTU) mixtures improve the effectiveness and ability of water to adhere to fuel. USDA Forest Service Specification 5100 - 304d defines the specifications for long - term fire retardants for wildfire suppression activities in the United States (these specifications are also adopted in several other countries).

[0003] As described above, long-acting flame retardants are conventionally prepared in centralized manufacturing facilities that form dry powders or liquid concentrates (LCs). These dry powders or LCs are then shipped to deployment areas such as air tanker bases that support aviation fire management activities. At such bases, the dry powders or LC flame retardants are mixed with water to form ready-to-use (RTU) flame retardant products, which are then loaded onto various types of aircraft deployed to drop the RTU products onto or near fires. Examples of the various aircraft used to drop flame retardants onto fires include single-engine air tankers (SEATs) with flame retardant carrying capacities of 800 gallons or less, large air tankers (LATs) with flame retardant carrying capacities of up to 8000 gallons (e.g., 2000-4000 gallons), and very large air tankers (VLATs) with flame retardant carrying capacities exceeding 8000 gallons.

[0004] The U.S. National Wildfire Coordination Group (NWCG) has published the Interagency Retardant Base Planning Guide (February 2006) and the NWCG Standards for Airtanker Base Operations (PMS508, June 2022).

[0005] At a given flame retardant air tanker base, a “mix master” is qualified to prepare ready-to-use (RTU) flame retardant products for loading onto air tankers by mixing dry powder or LC with water in specified ratios. The mix master works in a flame retardant “mixing plant” constructed in the air tanker loading area (or “pit”) at the air tanker base, which includes various equipment to facilitate the mixing of dry powder or LC with water. Figure 1 shows the elements of a conventional LC mixing plant at an air tanker base.

[0006] As shown in Figure 1, with regard to liquid concentrate (LC) flame retardants in particular, a conventional LC mixing plant includes at least one tank for containing the LC flame retardants. Some examples of conventional LC flame retardants that would be diluted and mixed in a conventional LC mixing plant shown in Figure 1 include the PHOS-CHeK® LC95 series and LCE20-FX liquid concentrates, which have viscosities in the range of about 100 to 400 centipoise (cP).

[0007] The conventional LC mixing plant shown in Figure 1 also includes a water tank and a manually operated proportional mixing valve for mixing LC flame retardants with water according to a specified mixing ratio to produce a ready-to-use (RTU) flame retardant product ("mixture"). The conventional LC mixing plant may also include a gas-driven filling pump for loading the RTU flame retardant product into an air tanker, and various piping (e.g., 4-inch diameter pipes or hoses) for interconnecting the LC container, solvent tank, manually operated proportional mixing valve, and filling pump. As will be understood by those skilled in the art, this type of conventional LC mixing plant does not require electricity to operate.

[0008] As shown in Figure 1, the output of the filling pump requires a flow meter to detect the flow rate (e.g., gallons / minute) and density (or specific gravity) of the RTU flame retardant product as it is loaded onto the air tanker. The U.S. Department of Agriculture's Forest Service requires that mass flow meters be used for all aircraft loading applications "to ensure that safe aircraft load limits are not exceeded, to assist in loading optimization, and to ensure that flame retardant contractors are paid fair compensation" (Interagency Retardant Base Planning Guide, February 2006, p. 40). The mass flow meter must be installed on the loading line in such a manner that each plane load of the RTU product is quantified and the product density is monitored. The target flame retardant supply rate is 400-500 gallons per minute for large air tankers (LATs) and 200-300 gallons per minute for single-engine air tankers (SEATs) (Interagency Retardant Base Planning Guide, February 2006, p. 35). An example of a conventional flow meter is a micromotion® flow meter that utilizes a Coriolis flow tube that vibrates in opposite directions when the fluid flows through the tube and the drive coil is excited, causing the tube to vibrate. As will be understood by those skilled in the art familiar with the operation of air tanker bases, given the requirements specified in the Interagency Retardant Base Planning Guide, February 2006, the flow meter is generally the final component in the flow path of RTU flame retardant products upstream of the air tanker's supply tank.

[0009] Regarding quality control of RTU flame retardant products, as shown in Figure 1, a sampling valve located downstream of a manually operated proportional mixing valve and upstream of a gas-driven filling pump is employed to allow sampling of small amounts of RTU products for analysis using a portable refractometer. Such portable refractometers are conventionally used regularly at flame retardant air tanker bases to determine the amount of flame retardant salt in a sample of RTU flame retardant products. The concentration of flame retardant salt in the RTU product determines the density (mass per unit volume) of the RTU product, and the density determines the refractive index (ability to bend light) of the RTU product. A refractometer is employed to measure this refractive index, and the refractive index is correlated with the salt content and density. Understanding the density (or specific gravity) of the RTU product is important in determining the weight of the air tanker after the RTU product has been loaded.

[0010] According to Section 4.3.2 of U.S. Department of Agriculture Forest Service Specification 5100-304d, "The refractometer reading of a properly mixed flame retardant should be determined using a portable refractometer having an arbitrary scale found on an industrial fluid tester or, if necessary, a Brix scale" (as will be readily apparent to those skilled in the art, the arbitrary scale found on an industrial fluid tester is known as the 10440VP arbitrary scale). Therefore, as shown in Figure 1, the mix master (or other authorized pit personnel at the flame retardant air tanker base) conventionally measures the refractive index of the RTU product using a portable refractometer, and as described above, the refractive index correlates with the concentration of flame retardant salts in the RTU product. For this purpose, the mix master applies a small sample of the RTU product to the refractometer prism and holds the refractometer relative to the light source to take a reading. Such manual measurements of the refractive index of the RTU product are generally performed at least once per aircraft loadout. [Overview of the Initiative]

[0011] The inventors recognized and understood that conventional flame retardant mixing operations have several drawbacks, particularly with respect to liquid concentrate (LC) flame retardants. Firstly, mixing LC flame retardants with water is generally a time-consuming process, which is problematic in firefighting operations where time is of the essence (for example, it may take more than 20 minutes to thoroughly mix LC with water to form an RTU product for firefighting purposes). Therefore, the time required to dilute and mix LC flame retardants with water to produce an RTU flame retardant product can limit how quickly a forest fire can be extinguished. Other problems in conventional LC mixing operations include quality control and batch-to-batch variability (e.g., variations in the concentration and / or homogeneity of the RTU product over time), which can negatively affect the ability to effectively extinguish fires.

[0012] The inventors further recognized and understood that the above and further challenges arise when relatively high-viscosity liquid concentrate (LC) flame retardants are used to prepare RTU flame retardant products. U.S. Department of Agriculture Forest Service Specification 5100-304d specifies the viscosity range for mixed RTU flame retardant products in Chapter 1.2.5 as follows: JPEG2026525194000002.jpg23170

[0013] The viscosity classification in the chart above applies to mixed RTU flame retardant products, but can also be applied to LC for comparative and explanatory purposes. In particular, the inventors considered using LC with a viscosity above the "high viscosity" range shown in the chart above (e.g., LC in the range of approximately 1500 cp to 3000 cp, hereinafter referred to as "ultra-high" viscosity) without using water to prepare RTU flame retardant products (for comparison, the PHOS-CHeK® LC95 series and the LCE20-FX liquid concentrate mentioned in the background section have a viscosity in the range of approximately 100 to 400 cP, which falls within the "low viscosity" range shown in the chart above).

[0014] With regard to the use of “ultra-high” viscosity LCs considered by the inventors, some examples of such “ultra-high” viscosity LC flame retardants include, but are not limited to, magnesium chloride (MgCl) salt-containing LCs, such as those disclosed in U.S. Patent No. 1,0960249, issued March 30, 2021, titled “Long-term Fire Retardant With Corrosion Inhibitors and Methods for Making and Using Same,” which is incorporated herein by reference. It should be understood that other LCs, such as those disclosed in one or more of the following U.S. patents, published patent applications, or patent applications, are also considered by the inventors for use relating to the concept of the invention disclosed herein. JPEG2026525194000003.jpg116170

[0015] LC flame retardants with ultra-high viscosities in the range of approximately 1500 cP to 3000 cP present specific challenges in the preparation of RTU flame retardant products, at least to some extent, due to the influence of their extremely high viscosity on the flow rate of the LC flame retardant.

[0016] More specifically, as will be immediately apparent to those skilled in the art, Poiseuille's law in fluid dynamics gives the relationship between the viscosity of a fluid (i.e., an incompressible Newtonian fluid in laminar flow), the length of a cylindrical pipe with a constant circular cross-section through which the fluid flows, and the pressure drop due to the fluid's viscosity, as follows: JPEG2026525194000004.jpg102165

[0017] From the above, it should be clear that viscosity is generally inversely proportional to flow rate. It should also be understood that Poiseuille's law does not apply under the limitations of very low viscosity and wide and / or short pipes (for example, low viscosity or wide pipes may result in turbulence, requiring a more complex relationship, but even when turbulence is a factor, Poiseuille's law provides a reasonable approximation of how flow rate changes with fluid viscosity and pipe radius).

[0018] Referring again to Figure 1, a conventional LC mixing plant may include a filling pump downstream of a manually operated proportional mixing valve to pump the RTU flame retardant product into an air tanker. The manually operated proportional mixing valve is sequentially connected to the LC container and solvent tank via pipes, respectively. The pressure (or suction force) applied by the gas-driven filling pump is applied to both water and LC to produce the RTU product, drawing these components through pipes and the manually operated proportional mixing valve.

[0019] In particular, the first pressure exerted by the water in the solvent tank (referred to here as the "water head pressure") and the second pressure (or suction force) exerted by the pump create a pressure difference according to Poiseuille's law, which affects the volumetric flow rate of water in the mixing plant. Similarly, the third pressure exerted by the LC in the LC container (referred to here as the "LC head pressure") and the second pressure (or suction force) exerted by the pump create a pressure difference, which affects the volumetric flow rate of LC in the mixing plant. For relatively low-viscosity LC (e.g., PHOS-CHeK® LC95 series and LCE20-FX liquid concentrates), the pump's action on both water and LC results in sufficiently equivalent flow rates for each (a given pipe of equivalent or identical length and radius is used to transport water and LC).

[0020] Under these relatively equivalent viscosity components, specific mixing ratios of LC and water can be effectively achieved to produce RTU products by manual operation of a proportional mixing valve. In particular, a manually operated proportional mixing valve is generally positioned by a mix master that varies the first opening size in the valve for water and the second opening size in the valve for the LC flame retardant (essentially varying the radius in Poiseuille's Law for each of LC and water). The varied opening sizes then adjust the flow rates of each component so that they mix within the valve in order to achieve the specified mixing ratio for the RTU product. Thus, the ratio of the opening size for water to the opening size for LC in the valve generally correlates with the specified mixing ratio for the RTU flame retardant product.

[0021] On the other hand, the inventors recognized and understood that achieving the specified mixing ratio to produce RTU flame retardant products using conventional manually operated proportional mixing valves is even more difficult for ultra-high viscosity LC flame retardants (e.g., magnesium chloride salt-containing LC with a viscosity in the range of 1500 cp to 3000 cp).

[0022] More specifically, referring back to the above Poiseuille's law, due to the significantly different viscosities of the ultra-high viscosity LC flame retardant and water, LC flame retardant and water with significantly different respective flow rates will flow into the proportional mixing valve. This is the case assuming the same or similar pipe radii and lengths (for example, consider the difference when drinking thick milkshakes and milk through the same straw) and the same pressure difference for both LC and water (generated by the filling pump and assuming the same head pressure for LC and water). This predicted difference in the respective flow rates under these different viscosity conditions is further complicated by recognizing that the assumption of the same head pressure does not hold. In particular, considering the ultra-high viscosity LC flame retardant, the head pressure of LC in the LC container and the head pressure of water in the solvent tank will be significantly different. These situations are further complicated by the constantly changing head pressure of LC in the LC container as more and more LC flame retardant from the LC container is used to produce the RTU flame retardant product.

[0023] The inventors understood that, considering the above situations of different viscosities for LC and water and the changing head pressure of LC, the manually operated proportional mixing valve employed in a conventional LC mixing plant as shown in FIG. 1 is not effective in reliably mixing ultra-high viscosity LC and water to produce the RTU product. In particular, the inventors recognized that, in order to effectively achieve the specified mixing ratio and desired concentration of the flame retardant salts in the RTU flame retardant product, the proportional mixing valve of the LC mixing plant needs to operate dynamically to periodically change (for example, continuously change in some cases) the respective opening sizes for the ultra-high viscosity LC flame retardant and water in the valve, and accordingly adjust the corresponding flow rates. More generally, the inventors recognized the need to dynamically control the respective flow rates of the ultra-high viscosity LC flame retardant and water, particularly from the perspective of the large viscosity difference and the constantly changing head pressure of LC in the LC container (regardless of whether a proportional mixing valve is used to mix the above components).

[0024] In view of the foregoing, the concept of the invention disclosed herein is directed toward an improved mixing plant for the dilution and effective mixing of a high-viscosity, long-acting flame retardant liquid concentrate with water to produce an RTU flame retardant product having a desired concentration of flame retardant salt. Furthermore, the improved mixing plant for dilution and effective mixing is also applicable to low-viscosity concentrates for producing an RTU flame retardant product. In exemplary embodiments, the effective mixing of high-viscosity LC and water is achieved to some extent by automated feedback control of the respective flow rates of LC and water. To facilitate improved quality control of the RTU product, in-line detection of the RTU product is employed to regularly measure and digitally record one or more parameters representing the concentration of flame retardant salt in the RTU as the RTU product is produced. One or more signals representing the measured parameters are used as feedback to automatically adjust the flow rates of LC and water to achieve a target concentration (e.g., weight percent) of flame retardant salt in the RTU product and a target flow rate for the RTU product (to facilitate loading onto an air tanker).

[0025] In one aspect, the technology described herein relates to a mixing plant that provides a ready-to-use (RTU) fire retardant product containing at least one fire retardant compound for aircraft mounting. The mixing plant includes a water tank for holding water, a liquid concentrate (LC) container for holding a liquid concentrate (LC) fire retardant containing at least one fire retardant compound, where the LC head pressure of the LC fire retardant in the LC container changes as the LC fire retardant is consumed to provide the RTU fire retardant product, an LC container, a single automated proportional mixing valve fluidly coupled to the water tank and the LC container to form the RTU fire retardant product by mixing water and the LC fire retardant, at least one conduit fluidly coupled to the single automated proportional mixing valve and a flow meter to convey the RTU fire retardant product from the single automated proportional mixing valve, at least one pump fluidly coupled to the at least one conduit to pump the RTU fire retardant product through the at least one conduit, an in-line refractometer positioned within the at least one conduit between the single automated proportional mixing valve and the flow meter to be in fluid contact with the RTU fire retardant product to measure the in-line refractive index of the RTU fire retardant product in the at least one conduit, and at least one controller communicatively connected to the in-line refractometer and the single automated proportional mixing valve, the at least one controller automatically adjusting at least one flow variable for each of the LC fire retardant and water by the single automated proportional mixing valve based at least in part on the in-line refractive index measured by the in-line refractometer to achieve a target refractive index of the RTU fire retardant product in the range of 10 to 30 for the 10440VP arbitrary scale.

[0026] In one aspect, the technology described herein relates to a mixing plant. The water tank includes a water level sensor to automatically replenish additional water to the water tank as water is consumed to provide the RTU fire retardant product in order to maintain a substantially constant water head pressure at the outlet of the water tank.

[0027] In some embodiments, the technology described herein relates to a mixing plant, which further includes a first operating valve coupled to the outlet of a water tank and connected to at least one controller, the first operating valve responding to a first signal output by at least one controller to open and close the first operating valve; and a second operating valve coupled to the outlet of an LC container and connected to at least one controller, the second operating valve responding to a second signal output by at least one controller to open and close the second operating valve.

[0028] In some embodiments, the technology described herein relates to a mixing plant in which at least one pump is communicated to at least one controller and controls the flow rate of at least one pump in response to at least one pump control signal output by at least one controller.

[0029] In some embodiments, the technology described herein relates to a mixing plant, which further includes a flow meter, and at least one controller is connected to an inline refractometer, a flow meter, and a single automated proportional mixing valve, which automatically adjusts at least one flow parameter for LC flame retardant and water, respectively, by the single automated proportional mixing valve, based at least to some extent on the inline refractive index measured by the inline refractometer and the inline density of the RTU flame retardant product measured by the flow meter, in order to achieve a target refractive index of the RTU flame retardant product in the range of 8 to 30 for an arbitrary scale of 10440VP.

[0030] In some embodiments, the techniques described herein relate to a method for providing a ready-to-use (RTU) flame retardant product containing at least one flame retardant compound, the method comprising: A) forming an RTU flame retardant product by producing a mixture of water and a liquid concentrate (LC) flame retardant containing at least one flame retardant compound, wherein the LC flame retardant has a viscosity in the range of 1500 centipoise (cP) to 3000 cP; B) measuring at least one parameter representing the concentration of at least one flame retardant compound in the mixture; and C) automatically adjusting at least one flow parameter for each of the LC flame retardant and water, based at least to some extent on B), to achieve a target weight percentage of at least one flame retardant compound in the RTU flame retardant product in the range of 8% to 12%, and a flow rate for the RTU flame retardant product in the range of 200 gallons / min to 1000 gallons / min.

[0031] In some embodiments, the technology described herein relates to a method for providing a ready-to-use (RTU) flame retardant product for use on an aircraft, wherein the RTU flame retardant product contains at least one flame retardant compound, and the method comprises the steps of A) forming an RTU flame retardant product by A) flowing water from a water tank through a single automated proportional mixing valve and operating at least one pump to flow a liquid concentrate (LC) flame retardant containing at least one flame retardant compound from a liquid concentrate (LC) container, wherein the LC head pressure of the LC flame retardant in the LC container changes during A), and the RTU flame retardant product is pumped at a flow rate in the range of 200 gallons / min to 1000 gallons / min through at least one conduit coupled between the single automated proportional mixing valve and a flow meter associated with the aircraft. The method includes the steps of: B) automatically and repeatedly measuring the inline refractive index of the RTU flame retardant product by an inline refractometer placed in at least one conduit between a single automated proportional mixing valve and an aircraft-related flow meter as the RTU flame retardant product is pumped through at least one conduit to generate multiple refractive index measurements for the RTU flame retardant product; and C) automatically adjusting or maintaining at least one flow parameter for LC flame retardant and water, respectively, by the operation of the single automated proportional mixing valve, based at least to some extent on the multiple refractive index measurements generated in B), in order to achieve a target refractive index of the RTU flame retardant product in the range of 8 to 30 for any 10440VP scale.

[0032] In some embodiments, the techniques described herein relate to methods, wherein the LC flame retardant has a viscosity in the range of 1500 centipoise (cP) to 3000 cP.

[0033] In some embodiments, the techniques described herein relate to methods, where in C), the target weight percentage of at least one flame retardant compound in the RTU flame retardant product is in the range of 8% to 12%.

[0034] In some embodiments, the techniques described herein relate to methods, and in C), the target refractive index of the RTU flame retardant product is in the range of 8.5 to 20.0 on an arbitrary scale of 10440VP.

[0035] In some embodiments, the techniques described herein relate to methods, wherein at least one flame retardant compound comprises at least one of magnesium chloride, ammonium phosphate, or polyphosphate.

[0036] In some embodiments, the techniques described herein relate to methods, and A) further includes the step of maintaining the water head pressure of the water in the water tank substantially constant during A).

[0037] In some embodiments, the techniques described herein relate to methods, which further include the step of storing a digital record of at least some of the multiple refractive index measurements generated in B).

[0038] In some embodiments, the techniques described herein relate to methods, which further include, prior to A), receiving a first user input via a user interface regarding a target mixing ratio of water and LC flame retardant to form an RTU flame retardant product, and adjusting the initial state of a single automated proportional mixing valve, at least to some extent based on the target mixing ratio, so that at least one flow variable for each of the LC flame retardant and water is initialized by the single automated proportional mixing valve.

[0039] In some embodiments, the technology described herein relates to a method, wherein a water tank includes a first operating valve at the outlet of the water tank, and an LC container includes a second operating valve at the outlet of the LC container, and the method further includes, prior to A), the step of automatically opening the first and second operating valves after adjusting the initial state of a single automated proportional mixing valve.

[0040] In some embodiments, the techniques described herein relate to methods, the methods further comprising: receiving a second user input via a user interface, prior to A), relating to a target flow rate for the RTU flame retardant product; and, in A), operating at least one pump to draw water and LC flame retardant through a single automated proportional mixing valve by gradually increasing the flow rate of the RTU flame retardant product to a target flow rate.

[0041] In some embodiments, the techniques described herein relate to methods, where C) is performed after the flow rate of the RTU flame retardant product reaches the target flow rate.

[0042] In some embodiments, the techniques described herein relate to methods, which further include, prior to A), receiving a third user input via a user interface regarding a target refractive index range for an RTU flame retardant product.

[0043] In some embodiments, the techniques described herein relate to methods, and C) further include the steps of: C1) comparing a first refractive index measurement among a plurality of refractive index measurements generated in B) at a first time with a range for a target refractive index of the RTU flame retardant product; C2) maintaining at least one flow variable for each of the LC flame retardant and water by a single automated proportional mixing valve if the first refractive index measurement of the RTU flame retardant product is within the range for a target refractive index of the RTU flame retardant product; and C3) adjusting at least one flow variable for each of the LC flame retardant and water by a single automated proportional mixing valve if the first refractive index measurement of the RTU flame retardant product is not within the range for a target refractive index of the RTU flame retardant product.

[0044] In some embodiments, the techniques described herein relate to methods, and C) further include the step of stopping at least one pump in A) if C4) a fourth user input relating to stopping the operation of at least one pump is received via the user interface, and C5) if: a fifth user input relating to a preset amount of RTU flame retardant product is received via the user interface, and the amount of RTU flame retardant product pumped through at least one conduit is equal to, approximately equal to or greater than, a preset amount of RTU flame retardant product, then the step of stopping at least one pump in A).

[0045] In some embodiments, the techniques described herein relate to methods, the methods further comprising step C6) repeating step C1) and either step C2) or C3) using a second refractive index measurement from a plurality of refractive index measurements at a second time.

[0046] In some embodiments, the techniques described herein relate to methods, wherein a first refractive index measurement of the RTU flame retardant product is not within the range of the target refractive index of the RTU flame retardant product, and C3) includes the step of operating a single automated proportional mixing valve to adjust at least one flow parameter for each of the LC flame retardant and water such that the in-line refractive index of the RTU flame retardant product changes by about 0.1 with respect to an arbitrary scale of 10440VP in B).

[0047] In some embodiments, the techniques described herein relate to methods, where C6) includes the step of waiting for a predetermined period following C6a) and C3), and C6b) after waiting for a predetermined period, repeating step C1) and either step C2) or C3) in a second time using a second refractive index measurement from a plurality of refractive index measurements.

[0048] In some embodiments, the techniques described herein relate to methods, and B) includes the steps of B1) automatically and repeatedly measuring the inline refractive index of an RTU flame retardant product by an inline refractometer placed in at least one conduit between a single automated proportional mixing valve and an aircraft-associated flow meter as the RTU flame retardant product is pumped through at least one conduit in order to generate a plurality of refractive index measurements for the RTU flame retardant product; and B2) automatically and repeatedly measuring the inline density of an RTU flame retardant product by an aircraft-associated flow meter as the RTU flame retardant product is pumped through at least one conduit in order to generate a plurality of density measurements for the RTU flame retardant product; and C) automatically adjusting or maintaining at least one flow variable for LC flame retardant and water, respectively, by a single automated proportional mixing valve, based at least to some extent on the plurality of refractive index measurements generated in B1) and the plurality of density measurements generated in B2), in order to achieve a target refractive index of the RTU flame retardant product in the range of 8 to 30 for an arbitrary 10440VP scale.

[0049] All combinations of the above concepts and the additional concepts described below in more detail (provided that the concepts are not mutually contradictory) constitute part of the subject matter of the invention disclosed herein. In particular, all combinations of the claimed subject matter appearing at the end of this disclosure constitute part of the subject matter of the invention disclosed herein. The technical terms used herein that may appear in any disclosure incorporated by reference should be given meanings that most closely correspond to the specific concepts disclosed herein.

[0050] Those skilled in the art will understand that the drawings are primarily for illustrative purposes and do not limit the scope of the subject matter of the inventions described herein. The drawings are not necessarily to scale, and in some cases, various aspects of the subject matter of the inventions disclosed herein may be exaggerated or enlarged in the drawings to facilitate understanding of various features. In the drawings, similar reference numerals refer to generally similar features (e.g., functionally and / or structurally similar elements). [Brief explanation of the drawing]

[0051] [Figure 1] Figure 1 shows the individual components of a conventional LC mixing plant at an air tanker terminal. [Figure 2] Figure 2 shows the mixing system of the invention for preparing (e.g., mixing or diluting) a long-acting flame retardant for fire application according to an exemplary embodiment. [Figure 3] Figure 3 shows a method for providing a ready-to-use (RTU) flame retardant product for use in aircraft, the RTU flame retardant product containing at least one flame retardant compound relating to this technology. [Figure 4] Figure 4 shows a method for providing an RTU flame retardant product containing at least one flame retardant compound related to this technology. [Figure 5] Figure 5 shows a method for providing an RTU flame retardant product containing at least one flame retardant compound related to this technology. [Modes for carrying out the invention]

[0052] Ingredients of liquid concentrate LC flame retardants may contain one or more flame retardant compounds. These flame retardant compounds may include one or more inorganic compounds, one or more organic compounds, or a combination thereof. Table 1 below shows exemplary compounds, and any one or more of these may be used alone or in combination as flame retardant compounds in the LC flame retardants relating to this technology. JPEG2026525194000005.jpg194170 JPEG2026525194000006.jpg252161JPEG2026525194000007.jpg37170

[0053] The flame retardant compound may be a salt. The salt may be a phosphate. Preferably, the phosphate is an industrial-grade phosphate with a low concentration of heavy metals. The phosphate may include ammonium salts of ortholine, pyroline, tripolyphosphate, or tetrapolyphosphate. The phosphate in the LC flame retardant composition may include one or more of the following: ammonium orthophosphate, ammonium pyrophosphate, and ammonium polyphosphate having an average chain length of less than 20 phosphorus atoms. For example, the phosphate may include at least one of diammonium phosphate (DAP), diammonium orthophosphate (DAP), monoammonium phosphate (MAP), monoammonium orthophosphate (MAP), and ammonium polyphosphate (APP).

[0054] Instead of (or in addition to) ammonium salts of ortho, pyro, tripoly, or tetrapolyphosphates, the phosphate may contain sodium phosphate salts. Sodium phosphate salts may include sodium salts of mono, di, tri, tetra, and polyphosphates. Sodium phosphate salts in LC flame retardants may include one or more of the following: monosodium phosphate (MSP), disodium phosphate (DSP), disodium phosphate hydrate, sodium ammonium phosphate (SAP), sodium ammonium phosphate hydrate (SAP-H), sodium tripolyphosphate (STPP), trisodium phosphate (TSP), and mixtures thereof. Disodium phosphate may be an anhydrous substance substantially free of hydrate. Alternatively, or in combination with anhydrous disodium phosphate, disodium phosphate may be a hydrate substantially free of anhydrous. This hydrate has the chemical formula Na2HPO4(H2O). x It can have a ratio of approximately 1 to approximately 12. For example, x may be equal to at least one of 2, 7, 8, or 12. Disodium phosphate is a multiple different hydrate Na2HPO4(H2O) y The mixture may contain such a mixture that, at the time of measurement, y represents the average weight of the hydrates in the mixture, and therefore y is not necessarily an integer. For example, the average weight of y may be about 2.0 to about 12.0, preferably about 1.5 to about 11.5, more preferably about 2.5 to about 10.5, and more preferably about 3.5 to about 9.5.

[0055] Sodium ammonium phosphate may be an anhydrous form that is substantially free of hydrates. Alternatively, or in combination with anhydrous sodium ammonium phosphate, sodium ammonium phosphate may be a hydrate. The hydrate has the chemical formula NaPO4HNH4(H2O). x It may have a value of approximately 1 to approximately 4. For example, x may be equal to at least one of 1, 2, 3, or 4. Disodium phosphate is a multiple different hydrate NaPO4HNH4(H2O) y The mixture may contain such a mixture that, when measured, y represents the average weight of the hydrates in the mixture, and therefore y is not necessarily an integer. For example, the average weight of y may be about 1.0 to about 4.0, preferably about 1.2 to about 3.9, more preferably about 1.4 to about 3.8, and more preferably about 1.6 to about 3.6. The sodium ammonium phosphate hydrate is preferably sodium ammonium phosphate tetrahydrate (SAP-TH) having the chemical formula NaPO4HNH4(H2O)4.

[0056] Instead of (or in addition to) ammonium salts and / or sodium phosphates of ortho, pyro, tripoly, or tetrapolyphosphates, the phosphate may be a calcium phosphate. The calcium phosphate may include ortho phosphates, dihydrogen phosphates and monohydrogen phosphates and / or calcium salts of diphosphates and polyphosphates. The calcium phosphate in the LC flame retardant may include one or more of the following: monocalcium phosphate (MCP), dicalcium phosphate (DCP), tricalcium phosphate (TCP), octacalcium phosphate (OCP), didicalcium diphosphate, tricalcium phosphate, hydroxyapatite, apatite, or tetracalcium phosphate (TTCP).

[0057] Instead of (or in addition to) ammonium salts, sodium phosphates, and / or calcium phosphates of ortho, pyro, tripoly, or tetrapolyphosphates, the phosphate may be potassium phosphate. The potassium phosphate in the LC flame retardant may include one or more of the following: monopotassium phosphate (MKP), dipotassium phosphate, or tripotassium phosphate.

[0058] The phosphate of the LC flame retardant may contain an ammonium source. The ammonium source may be an ammonium salt. The ammonium source may be an ammonium phosphate salt. For example, if the phosphate contains ammonium, the ammonium phosphate salt in the LC flame retardant may include one or more of the following: diammonium phosphate (DAP), diammonium orthophosphate (DAP), monoammonium phosphate (MAP), monoammonium orthophosphate (MAP), ammonium polyphosphate (APP), sodium ammonium phosphate (SAP), or sodium ammonium phosphate hydrate (SAP-H). Instead of (or in addition to) ammonium phosphate salts, the LC flame retardant may contain a non-phosphate ammonium source. The non-phosphate ammonium source in the LC flame retardant may include one or more of the following: ammonium chloride, ammonium acetate, ammonium citrate, or ammonium sulfate. The flame retardant concentrate does not have to contain ammonium phosphate, but when the flame retardant concentrate is diluted with water to produce the final flame retardant product, the final flame retardant product may contain ammonium phosphate by ion exchange in the solution. The LC flame retardant may contain a mixture of phosphates.

[0059] In one embodiment, the phosphate mixture has an ammoniacal nitrogen to phosphorus molar ratio (N / P molar ratio) of about 0.4 to about 1.4, preferably about 0.6 to about 1.3, and more preferably about 0.8 to about 1.1. For example, the N / P molar ratio is less than about 1.1 or about 1. For example, the N / P molar ratio may be 1.05 or less, 1.04 or less, 1.03 or less, 1.02 or less, 1.01 or less, or 1.00 or less. In another embodiment, the N / P molar ratio is higher than about 1.9, for example, about 1.9 to about 3.0, preferably about 2.0 to about 2.9, and more preferably about 2.1 to about 2.7. For example, the N / P molar ratio may be 1.95 or more, 1.96 or more, 1.97 or more, 1.98 or more, 1.99 or more, or 2.0 or more. As used herein, "ammonia nitrogen" or "phosphorus" refers to the molar ratio of nitrogen to phosphorus (N / P molar ratio), respectively, and any ammonia nitrogen (NH4) present in the mixture from any of the sources listed in Table 1. + ) or phosphorus. For example, the N / P ratio will not include nitrogen or phosphorus derived from dyes not listed in Table 1.

[0060] The liquid concentrate may further contain a corrosion inhibitor to reduce corrosion of various components exposed to the liquid concentrate (e.g., pipes or tubes of the mixing system 100) and / or various components exposed to the final diluted product (e.g., a spraying system used to distribute the final diluted product in an aircraft or ground vehicle). The components may be formed from a variety of materials, but are not limited to, brass, iron, aluminum, steel, copper, and magnesium.

[0061] The LC flame retardant and / or final dilution product may further contain a corrosion inhibitor. The corrosion inhibitor may include inhibitors for brass, iron, aluminum, steel, copper and / or magnesium. The corrosion inhibitor may also include inhibitors for any of the compounds listed in Table 1. The corrosion inhibitor for magnesium may include the corrosion inhibitors disclosed in Lamaka, SV et al., "Comprehensive screening of Mg corrosion inhibitors," Corrosion Science 128 (2017), which are incorporated hereby by reference in their entirety. The corrosion inhibitor may include alkyl (such as alkylamine) and / or one or more azoles. The corrosion inhibitor may include COBRATEC928, denatonium benzoate, benzoic acid, diammonium phosphate, monoammonium phosphate, WintrolSB 25Na, or a combination thereof. The corrosion inhibitor may include one or more azoles. The corrosion inhibitor may be Wintrol® Super Azole Mix (Wintrol® SAM-H90 by Wincom, Inc.). Wintrol® SAM-H90 is designed for aqueous applications. Wintrol® SAM-H90 provides corrosion resistance in highly corrosive environments with halogens such as chlorides. Optionally, Wintrol® SAM-H38Na may be used alone or in combination with Wintrol® SAM-H90 as a corrosion inhibitor. The corrosion inhibitor is not limited to, but may include sodium selenite, sodium stearate, sodium lauryl sulfate, stearic acid, sodium benzoate, sodium fluoride, sodium phosphate, monosodium phosphate (MSP), disodium phosphate (DSP), and disodium phosphate hydrate (Na2HPO4(H2O)). x (x is approximately 1 to 12), trisodium phosphate (TSP), monopotassium phosphate (MKP), dipotassium phosphate (DKP), dipotassium phosphate hydrate (K2HPO4(H2O) x (x is approximately 3 to 6), tripotassium phosphate, tripotassium phosphate hydrate (K3PO4(H2O) x(x is approximately 3 to approximately 9), monoammonium phosphate (MAP), diammonium phosphate (DAP), triammonium phosphate, triammonium phosphate hydrate, iron pyrophosphate, dibasic sodium fumarate, sodium fumarate, magnesium phosphate, benzotriazole derivatives, sodium salts of benzotriazole and its derivatives, aqueous mixtures of benzotriazole and its derivatives, benzotriazole-5-carboxylic acid, benzotriazole, butylbenzotriazole, sodium butylbenzotriazole, tolyltriazole derivatives, sodium salts of tolyltriazole and its derivatives, aqueous mixtures of tolyltriazole and its derivatives, tetrahydro Tolyltriazole, tolyltriazole, hydrogenated tolyltriazole and mixtures thereof, sodium tolyltriazole, sodium tolyltriazole (50% solution), 3-hydroxyphenyl-4-phenyl-5-mercapto-1,2,4-triazole (HPMT), 3-aminophenyl-4-phenyl-5-mercapto-1,2,4-triazole (APMT), 3,4-diphenyl-5-mercapto-1,2,4-triazole (DPMT), 3-cinnamyl-4-phenyl-5- Mercapto-1,2,4-triazole (CPMT), 1,8-naphthalaldehyde (1,8-napthalaldehydic) acid, octadecylphosphonic acid, sodium dodecylsulfonate (SDBS), Wintrol® BBT-25Na, Wintrol® BBT, Wintrol® THT-T, Wintrol® THT-35PG, Wintrol® THT-50K, Wintrol® SAM-H90, Wintrol SB 25Na, Wintrol® SAM-H38Na, Wintrol® SAM-H40(OS), Wintrol® SAM-B90, Berberine, Pyrrolidinebenzyl, Catechin, Lysergic Acid, Carmine, Fast Green, Aniline, Vanillin, Triethanolamine, Triethanolamine for Low Temperature Freezing (85% TEA and 15% Water), N,N,N',This may include N'-tetrakis(2-hydroxyethyl)ethylenediamine, tris(hydroxymethyl)aminomethane (TRIS), tris(hydroxymethyl)aminomethane hydrochloride (TRIS-HCl), p-chloroaniline, p-nitroaniline, p-methoxyaniline, p-methylaniline, sodium p-coumarate, sodium silicate, sodium molybdate, sodium molybdate dihydrate, disodium molybdate, disodium molybdate dihydrate, biopolymers (ramsang gum, xanthan gum, diutan gum, or welan gum), sodium fluoride silica (SSF), and dimercaptothiadiazole (DMTD), or a combination of the above.

[0062] The final diluted product may be uncolored (i.e., transparent, naturally colored, or without colorants) or may be colored with a colorant. The colorant may be a fade-resistant colorant, a non-fading colorant, or a combination of the two. The final diluted product has a first hue, which is a color, i.e., colorless or a color that harmonizes with the normal vegetation and / or ground of the deployment area. This first hue may be gray or white or a combination of the two. The colorant initially colors the final diluted product to a second hue, which contrasts with the hue of the ground vegetation. The colorant may be a fade-resistant component such as a dye, i.e., a dye dispersed in a matrix (i.e., a pigment), which fades over time and under ambient conditions to a colorless or lighter colored hue. The colorant may be a mixture of organic pigments (e.g., fluorescent pigments) and inorganic pigments (e.g., iron oxide, titanium oxide, and / or titanium dioxide). Preferably, the colorant is compatible with the flame-retardant salts described herein. Fading dyes may fade over time due to exposure to sunlight. Fading dyes may also be rapidly fading dyes designed to last from a few hours to several weeks, for example.

[0063] Dyes and pigments with multiple fade-resistant components can be used as colorants. The colorants may be dyes and / or pigments. For example, many water-soluble dyes fade rapidly, as do so-called fluorescent pigments (fluorescent dyes encapsulated in resin coatings or dispersed as emulsions in thermoplastic resins in forest flame retardant compositions), which also fade rapidly and provide a fade-resistant effect. The colorants may also be agricultural, pesticide, or food dyes, or combinations of red, pink, claret, and / or cherry blossom-colored dyes. Examples of fade-resistant dyes and pigments include, but are not limited to, CI Basic Red I dye, 6BL dye, Basic Violet II dye, CI Basic Violet 11:1 (tetrachlorohydrochlorite), CI Basic Red 1:1, Basic Yellow 40, Acid Fuchsin, Basic Fuchsin, New Fuchsin, Acid Red 1, Acid Red 4, Acid Red 8, Acid Red 18, Acid Red 27, Acid Red 37, Acid Red 88, Acid Red 97, Acid Red 114, Acid Red 151, Acid Red 183, Acid Red 183, Fast Red Violet 1B base, Solvent Red, Rhodamine B, Rhodamine 6G, Rhodamine 123, Rhodamine This includes min 110 chloride, erythrosine B, basacryl red, phloxine B, Bengal rose, direct red 80, direct red 80, Sudan red 7B, Congo red, neutral red, fluorescent red mega 480, fluorescent red 610, fluorescent red 630, fluorescent red mega 520, Pylaklor red S-361, Pylaklor scarlet LX-6364A, Pylam bright red LX-1895, Pylam coral LX-1801, FD&C red 3, FD&C red 4, FD&C red 40, FD&C red 4 Lake, D&C red 33, D&C red 33 Lake, and commercially available encapsulated dye pigments, such as the "AX" series pigments provided by Day-Glo Color Corp. of Cleveland, Ohio. The dye may be Liquitint 564 (λ=564nm) or Liquitint Agro Pink 564 (λ=564nm) from Milliken Company (Spartanburg, South Carolina). The colorant may be an organic pigment such as a fluorescent pigment.The fluorescent pigment may be a dispersion of Day-Glo Aurora pink or other pink, red, orange, crimson (or a combination of these four colors). The fluorescent pigment may be ultraviolet sensitive, substantially formaldehyde-free, and / or have LAB color intervals based on the International Commission on Illumination's LAB color space model, with an "L" value in the range of about 34 to about 89, an "a" value in the range of about 18 to about 83, and a "b" value in the range of about -61 to about 56.

[0064] The colorants may be those manufactured by Greenville Colorants (New Brunswick, New Jersey) or Milliken & Company (Spartanburg, South Carolina). For example, the colorants may be those suitable for use with the flame retardant salts described herein, such as those used in magnesium chloride dust control and roadbed stabilization formulations or magnesium chloride de-icing formulations. The colorants may be Elcomine Scarlet NAS, Elcomine Scarlet NAS EX, or Iron Oxide GC-110P from Greenville Colorants. The colorants may also be a combination of Liquitint 564 and Iron Oxide GC-110P.

[0065] The colorant in the final diluted product may be a dye, or it may contain a faded pigment of an encapsulated dye that does not contain an ultraviolet absorber. Compared to water-soluble dyes, encapsulated dye pigments are less likely to permanently stain the normal vegetation and / or ground in the deployment area. The faded component is present in an amount that gives the final diluted product a color (second hue) that is in contrast to the color of the vegetation and / or ground in the deployment area (usually green, blue-green, and / or brown). It is advantageous that the second hue is red, orange, or pink. The color of the dye may be red, orange, purple, or pink, or any combination of these four colors. Preferably, the dye is compatible with the flame-retardant salt described herein. Alternatively, if no colorant is added, the final diluted product may be colorless.

[0066] The colorant may contain a non-fading component, i.e., a component that is insoluble in the carrier solution and, once colored, does not necessarily fade after aerial spraying of the final diluted product. The non-fading component of the colorant is present in an amount sufficient to improve the aerial visibility of the composition when initially sprayed onto vegetation, provided that the amount of the non-fading component is less than that which prevents the composition from subsequently fading its neutral color. The colorant may be a combination of a fading component and a non-fading component. The non-fading component in the final diluted product may be iron oxide (Fe2O3 and / or Fe3O4). Iron oxide may be present in combination with the above-mentioned fading colorant and titanium dioxide, or on its own. The weight of the non-fading colorant may, in whole, contain at least 12 grams of the minimum value of non-fading colorant according to Specification 5100-304d (January 7, 2020), which is incorporated herein by reference.

[0067] The weight percentage of the colorant (e.g., fluorescent pigment) relative to the amount of flame retardant compound in the liquid concentrate is about 0.1% to about 15.0%, preferably about 0.2% to about 12.0%, more preferably about 0.3% to about 10.0%, and more specifically about 0.4% to about 8.0%. For example, the weight percentage of the colorant relative to the amount of flame retardant compound in the liquid concentrate is about 0.5% to about 5.0%.

[0068] The liquid concentrate may contain inorganic pigments. Inorganic pigments can act as colorants. Inorganic pigments may include, but are not limited to, iron oxide, titanium dioxide, magnesium hydroxide, cobalt blue, cerulean blue, malachite, earth green, raw umber, raw cienna, iron black, or burnt cienna. Iron oxide can act as a milking agent. Titanium dioxide can act as a pigment to give, for example, a white pigment. Titanium dioxide can also act as a photoresponsive material to produce opacity by scattering light or by protecting the components of the liquid concentrate from ultraviolet degradation.

[0069] The weight percentage of inorganic pigment relative to the amount of flame retardant compound in the liquid concentrate is about 0.02% to about 4.0%, preferably about 0.04% to about 3.5%, more preferably about 0.06% to about 3.0%, and more specifically about 0.08% to about 2.5%. For example, the weight percentage of inorganic pigment relative to the amount of flame retardant compound in the liquid concentrate is about 0.1% to about 2.0%.

[0070] The weight percentage of the total colorant relative to the amount of flame retardant compound in the liquid concentrate is about 0.1% to about 30.0%, preferably about 0.2% to about 28.0%, more preferably about 0.3% to about 25%, and more specifically about 0.4% to about 20.0%. For example, the weight percentage of the total colorant relative to the amount of flame retardant compound in the liquid concentrate is about 0.5% to about 18.0%.

[0071] The weight percentage of the flame retardant compound relative to the total weight of the liquid concentrate may be about 5% to about 85%, for example, about 20% to about 80%, preferably about 30% to about 75%, and particularly about 35% to about 70%. The weight percentage of the flame retardant compound relative to the total weight of the liquid concentrate may be in the range of about 8% to about 12%.

[0072] The liquid concentrate may be any liquid concentrate and / or intermediate liquid concentrate formed from the dry concentrates disclosed in U.S. Patent Application No. 16 / 894214 filed June 5, 2020, U.S. Patent Application No. 17 / 031024 filed September 24, 2020, U.S. Patent Application No. 17 / 214266 filed March 26, 2021, U.S. Patent Application No. 17 / 458002 filed August 26, 2021, and U.S. Patent Application No. 17 / 552196 filed December 15, 2021, all of which are incorporated by reference in their entirety.

[0073] The viscosity of the liquid concentrate can be in the range of about 10 cP to about 10,000 cP. For example, the viscosity of the liquid concentrate may be about 100 cP to about 8,000 cP, preferably about 500 cP to about 7,000 cP, more preferably about 1,000 cP to about 6,000 cP, more preferably about 1,500 cP to about 3,000 cP, and more preferably the viscosity may be about 1,750 cP to 2,250 cP at 70°C. For example, the viscosity of the liquid concentrate may be about 1,970 cP to about 2,090 cP at 70°C.

[0074] To form the final diluted product, the liquid concentrate may be diluted with water. In other words, the final diluted product contains a first amount of liquid concentrate and a second amount of water. The mixing ratio, defined as the water-to-liquid concentrate ratio, can be about 45:1 to about 0.2:1 (water:liquid concentrate), preferably about 20:1 to about 0.5:1, more preferably about 10:1 to about 0.75:1, and specifically about 5:1 to about 1:1. For example, the liquid concentrate may be diluted at a mixing ratio of 2:1 (water:liquid concentrate) to form the final diluted product. As another example, the liquid concentrate may be diluted at a mixing ratio of 1.895:1 (water:liquid concentrate) on a weight / weight basis.

[0075] The liquid concentrate can be diluted with water so that the final diluted product has a weight percentage of about 2% to about 70%, preferably about 5% to about 40%, and more preferably about 7% to about 30% of the flame retardant compound (e.g., salt). For example, the concentration of the flame retardant compound (e.g., salt) in the final diluted product is about 8% to about 25%.

[0076] The liquid concentrate can be diluted with water so that the final diluted product has a flame retardant concentration of about 300 to 900 grams per gallon of water, preferably about 450 to 800 grams per gallon of water, and more preferably about 500 to 750 grams per gallon of water.

[0077] The final diluted product is a long-acting forest fire retardant with improved aerial visibility against the direct or indirect initiation of forest fires. The resulting final diluted product may be an opaque, reddish suspension that is less prone to settling. The final diluted product may be mixed approximately every 7-10 days to ensure uniform density and homogeneity.

[0078] The final diluted product may be any of the final diluted products disclosed in the following U.S. Patent Application No. 16 / 894214 filed June 5, 2020, U.S. Patent Application No. 17 / 031024 filed September 24, 2020, U.S. Patent Application No. 17 / 214266 filed March 26, 2021, U.S. Patent Application No. 17 / 458002 filed August 26, 2021, U.S. Patent Application No. 17 / 552196 filed December 15, 2021, and U.S. Patent Application No. 18 / 061542 filed December 5, 2022. Each of the above applications is incorporated by reference in their whole.

[0079] The viscosity of the final diluted product can be adjusted to suit various aircraft and ground vehicles by adjusting the amount of thickener added to the liquid concentrate before dilution or by adjusting the dilution factor of the liquid concentrate. In some modifications, the final diluted product may be a medium-viscosity, long-acting flame retardant. The viscosity of the medium-viscosity diluted flame retardant may be in the range of 300 cP to 800 cP, and more preferably, the viscosity may be 460 cP to about 490 cP at 70°F.

[0080] In one embodiment, the final diluted product has a pH of about 4.0 to about 10.0, preferably 4.5 to about 9.8, more preferably about 5.0 to about 9.5, and more preferably about 5.5 to about 9.0. For example, the pH of the final diluted product may be approximately 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, 7.0, 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.6, 8.7, 8.8, 8.9, 9.0, or any value between 5.5 and 9.0. The solidification temperature of the final diluted product may be in the range of 15°F to 25°F. When mixed with water, the final diluted product may become a homogeneous, stable liquid.

[0081] Mixing system Figure 2 shows a mixing system 100 (also called a mixing plant) of the invention for preparing (e.g., mixing or diluting) a long-acting flame retardant for spraying on a fire, according to an exemplary embodiment. The mixing system 100 may be used to prepare a long-acting flame retardant diluted product by diluting a long-acting flame retardant liquid concentrate with a solvent such as water. The resulting diluted product is in a form suitable for extinguishing (e.g., suppressing, delaying, or controlling) a forest fire by aerial or ground spraying. In some modifications, the mixing system 100 may be located at or near the site of a firefighting operation (e.g., at an airfield near a forest fire), thereby enabling the mixing system 100 to prepare a final flame retardant diluted product that is convenient for deployment on a forest fire. In other modifications, the mixing system 100 may be located at other locations related to firefighting operations or the storage of flame retardants.

[0082] As described in more detail below, a flame retardant liquid concentrate is a viscous liquid containing one or more flame retardant compounds dissolved in water at high concentrations. For example, the viscosity of a liquid concentrate at room temperature can range from about 50 centipoise (cP) to about 5000 cP, or more generally from about 10 centipoise (cP) to about 10000 cP. For illustrative purposes, fluids that fall within this viscosity range include glycerin, corn syrup, and honey. For reference, the viscosity of water at room temperature is about 1 cP.

[0083] To produce a flame retardant dilution product suitable for spraying on fires, the liquid concentrate is mixed with water for dilution. However, the inventors recognized and understood that, due to the relatively high viscosity of the flame retardant liquid concentrate, it is conventionally difficult to mix the liquid concentrate with water in the correct ratio. This problem is exacerbated when mixing the liquid concentrate and water at relatively high flow rates (e.g., 500 gallons / minute). Despite these conventional mixing difficulties, the ability to effectively control the liquid concentrate-to-water ratio is important to ensure that the dilution product meets the specifications set by fire management services. For example, the U.S. Forest Service specifies criteria for forest flame retardants to qualify for use by the U.S. Forest Service, such as the criteria outlined in Forest Service Specification 5100-304d, which is incorporated herein by reference in its entirety.

[0084] The mixing system 100 addresses the above problem by providing a mixing system capable of effectively and accurately mixing a liquid concentrate with water at a desired volume-to-volume (e.g., gallon-to-gallon) water-to-liquid concentrate mixing ratio in the range of about 45:1 to about 0.2:1 (water:liquid concentrate). In one embodiment, the mixing ratio can be varied in very small increments (e.g., substantially continuously) throughout this range, despite the large viscosity difference between the liquid concentrate and water. In another embodiment, the mixing system 100 produces a diluted product at a production rate (also called flow rate) in the range of about 100 gallons / min (gpm) to about 1200 gpm (examples of production rates include, but are not limited to, 100 gpm, 500 gpm, 1000 gpm, or 1200 gpm).

[0085] As described in more detail below, in one exemplary embodiment, the mixing system 100 includes one or more "in-line" sensors, i.e., sensors placed in the flow of the dilution product, for detecting one or more measurable characteristics of the dilution product. One or more detected characteristics are input to a controller, which controls one or more valves and / or one or more pumps to change the flow rates of one or both of the water and the liquid concentrate, thereby changing the mixing ratio based at least to some extent on one or more detected characteristics of the dilution product.

[0086] The mixing system 100 may include an LC container 120 filled at least partially with a liquid concentrate 122 and a solvent container 130 (equivalently a water tank 130) filled at least partially with a solvent 132. The solvent 132 may be, for example, water, and may be added to the solvent container 130 through a solvent source 138. The distribution of the solvent 132 from the solvent source 138 is controlled by a float valve 136, which may be configured to distribute water into the solvent container 130 based on the liquid level of the solvent 132, for example, when the liquid level of the solvent 132 falls below a threshold. The float valve 136 may include a float 137 configured to float above the solvent 132 and be displaced by the solvent 132. If the liquid level of the solvent 132 is sufficiently high, the float 137 will be displaced so that the float valve 136 closes and the solvent 132 stops flowing.

[0087] The liquid concentrate 122 may be any suitable flame retardant compound relating to this technology, for example, the flame retardant compounds listed in Table 1. The liquid concentrate 122 may have an appropriate viscosity as described above, for example, about 1500 cp to about 3000 cp, but lower viscosities are also possible, for example, about 1 cP to about 50 cP, about 25 cP to about 75 cP, about 50 cP to about 150 cP, about 100 cP to about 800 cP, about 500 cP to about 1000 cP, and about 800 cP to about 1500 cP.

[0088] The liquid concentrate 122 and the solvent 132 can each be dispensed through their respective dispensing valves. For example, the LC container 120 may include an LC dispensing valve 124, and the solvent container 130 may include a solvent dispensing valve 134. The LC dispensing valve 124 and the solvent dispensing valve 134 are communicated to a controller 110, which may be configured to transmit one or more signals that control the operation of the LC dispensing valve 124 and / or the solvent dispensing valve 134. For example, the controller 110 opens the LC dispensing valve 124 and the solvent dispensing valve 134, allowing the liquid concentrate 122 and the solvent 132 to mix and form a final diluted product, which consumes both the solvent (e.g., water) and the LC flame retardant as they mix to form a final diluted product (e.g., an RTU flame retardant product).

[0089] The controller 110 may be connected to a user interface 112, which may be a computer, tablet, laptop, desktop, smartphone, touch panel, kiosk, or any suitable device for receiving information and / or commands from a user. The user interface 112 may include data storage and / or memory for storing information such as information relating to the operation of the mixing system 100. For example, the user interface 112 may be used to store a digital record of at least some of several measurements relating to refractive index, flow rate, viscosity, pH, density, or other suitable measurements.

[0090] The user may input one or more parameter values ​​for the final diluted product that can be produced by mixing the liquid concentrate 122 and the solvent 132 according to the parameter values. For example, the user may input one or more parameter values ​​for refractive index, density, viscosity, pH, mass flow rate, conductivity, flow rate, type of liquid concentrate 122, type of solvent 132, and / or selective ion concentration of the final diluted product.

[0091] The liquid concentrate 122 and the solvent 132 may flow through the piping 170 (or conduit 170). The mixing system 100 may include one or more pumps 150, including an LC pump 150a, a solvent pump 150b, and a final diluted product pump 150c. The pumps 150 may be any suitable type of pump, such as a mechanical pump or a siphon pump. Each of the pumps 150 may be located downstream of the LC distribution valve 124 and the solvent distribution valve 134. In an alternative embodiment, the LC pump 150a may be located upstream of the LC distribution valve 124, and the solvent pump 150b may be located upstream of the solvent pump 150b.

[0092] Each pump of pump 150 may further be configured to mix the dilution product discharged from the outlet port of the proportional mixing valve. Each pump may have a variable pumping speed. Controller 110 may further be connected to each pump and further be configured to modulate the variable pumping speed based on sensor data from pump 150 and / or other sensors in the mixing system 100. The mixing system 100 may further include a mixing joint 172, a fixed mixer fluidly coupled to the final dilution product pump 150c and / or the final dilution product valve 174 for mixing the final dilution product discharged from the outlet port of the final dilution product valve 174.

[0093] The mixing junction 172 is a body defining a cavity and may include a body having a first inlet port for introducing a liquid concentrate into the cavity, a second inlet port for introducing water into the cavity, and an outlet port for discharging a mixture of the liquid concentrate and water. The mixing junction 172 may further include a modulation element positioned within the cavity. The modulation element is movable within the cavity and can be positioned to partially or completely block the first inlet port and / or the second inlet port to change the proportion of liquid concentrate and / or water entering the cavity, and thus the mixing ratio of the liquid concentrate and water.

[0094] The modulation element may be coupled to an actuator that can be used to adjust the modulation element (for example, by moving or rotating the modulation element). The actuator may be a variety of actuators, including, but is not limited to, electric motors, solenoids, pneumatic actuators, hydraulic actuators, and any combination thereof. The actuator may have a handle for manual operation. The actuator may also be communicated to a controller 110 to receive control signals from the controller 110 and adjust the modulation element based on the control signals. For example, the control signals may be generated based on one or more states of the final diluted product discharged from the outlet port measured by one or more sensors of the measuring device 140.

[0095] As shown in Figure 2, one or more signals from a measuring device 140, which may represent an in-line concentration measurement of the final diluted product, are input to the controller 110. The controller 110 then controls the flow of one or more of the liquid concentrate 122, solvent 132, or final diluted product based on the in-line concentration measurement. The controller 110 may optionally receive other signals provided by a flow meter to facilitate automated control of the flow of the liquid concentrate 122, solvent 132, and / or final diluted product. In an exemplary embodiment, the measuring device 140 may include an in-line refractometer configured to measure the concentration of the final diluted product after mixing at the mixing junction 172, and examples of refractometers effectively employed by the inventors for this purpose include, but are not limited to, the L-Rix series from Anton Paar.

[0096] The mixing system 100 enables automated variable flow rate control for each of the liquid concentrate 122, solvent 132, and final diluted product based on one or more signals provided by the controller 110. These one or more signals are based on one or more inline concentration measurements from measuring devices 140 (e.g., inline refractive index measurements provided by an inline refractometer, one or more signals provided by a flow meter, etc.). In various embodiments of the invention, it will be seen that such automated variable flow rate control can be achieved in multiple ways. In embodiments, the mixing system 100 may include a plurality of measuring devices 140 located in various parts of the piping 170, the LC container 120, the solvent container 130, or any suitable part of the mixing system 100.

[0097] One or more sensors of the measuring device 140 may be positioned inline with the flow of the final diluted product to continuously and directly monitor the characteristics of the final diluted product generated by the mixing system. This can be achieved, for example, by positioning one or more sensors in the piping 170 or tubes carrying the final diluted product, in a side-stream sampling line fluid-coupled to the main piping or tubes, or on a window coupled to the piping 170. The flow rate of the final diluted product may be measured by a flow meter 160 which may be positioned in a portion of the piping 170 adjacent to an aircraft 180 (such as a firefighting air tanker) or an RTU product container 190.

[0098] The final diluted product may be stored or loaded after mixing. For example, the final diluted product may be stored as RTU product 192 in an RTU product container 190. The RTU product container 190 may be used to provide storage for the RTU product 192 (e.g., several hours, several days, several weeks, several months, etc.). The final diluted product may be loaded onto the aircraft 180 via a loading hose 176. The final diluted product may be loaded directly onto the aircraft 180 via a mixing joint 172 after mixing, or it may be loaded onto the aircraft 180 from the RTU product container 190.

[0099] In a non-limiting example, one or more sensors of the measuring device 140 may include a refractometer for measuring the refractive index of the diluted product, the refractive index of which may vary significantly in response to slight changes in the mixing ratio of the flame retardant liquid concentrate and water, and which is less affected by the presence of air bubbles in the diluted product. The components of a refractometer are generally susceptible to corrosive damage when exposed to magnesium chloride, or more generally, corrosive compounds such as halides, phosphates, sulfates, carbonates and / or hydroxides, but the mixed systems disclosed herein can reduce or, in some cases, mitigate corrosive damage to the refractometer by using a liquid concentrate containing a corrosion inhibitor.

[0100] The controller 110 may be configured to communicate with the pump 150 and control the flow of the liquid concentrate 122, solvent 132, and final dilution product using one or more measurements from the pump 150, the LC distribution valve 124, the solvent distribution valve 134, the final dilution product valve 174, and the measuring device 140. For example, the controller 110 may increase or decrease the speed of the LC pump 150a based on one or more refractive index measurements indicating the concentration of the liquid concentrate 122 in the final dilution product.

[0101] For example, in one embodiment of the invention, each variable pump responding to the controller 110 may be used for LC, water, and RTU products. The mixing joint for LC, water, and RTU products comprises a T-shaped or Y-shaped joint (conventionally also called a "pipe wye").

[0102] In another example of the invention, each adjustable opening valve, responsive to the controller 110, may be employed for LC and water respectively, along with a T-shaped or Y-shaped piping three-way branching joint and a single pump (which may also be responsive to the controller 110) for the RTU product.

[0103] In yet another example, an automated proportional mixing valve responsive to controller 110 may be employed together with a single pump (which may also be responsive to controller 110) for the RTU product downstream of the automated mixing valve. Alternatively, the automated proportional mixing valve responsive to controller 110 may be employed together with separate pumps (which may also be responsive to controller 110) for LC and water upstream of the automated proportional mixing valve. Other permutations and combinations of the above arrangements have also been considered by the inventors and should be readily understood by those skilled in the art who are interested in this disclosure.

[0104] The following are two non-limiting illustrative examples of the system and method of the invention relating to this disclosure. [Examples]

[0105] The mixing system includes the following: ·Water supply source A tank equipped with a float valve or other water level sensor that automatically activates to start refilling the tank and maintain a minimum head pressure when the water level falls below a predetermined level, and an operating valve at the outlet of the tank connected by a pipe to one port of an operating proportional mixing valve. ○The operating valve of the solvent tank is connected to a controller that can open and close the valve by transmitting a signal. ·Liquid concentrate source A tank having a liquid concentrate (LC), an operating valve for the tank, and a pipe connecting the valve of the LC container to one port of an operating proportional mixing valve. The LC container's operating valve is connected to a controller that can open and close the valve by transmitting a signal. A proportional mixing valve having one input port connected to the controller and via a pipe to the operating valve of the water supply source, a second input port connected via a pipe to the operating valve of the liquid concentrate (LC) supply source, and an output port. ○The operating proportional mixing valve is adjustable by transmitting a signal and is connected to a controller that can adjust the mixing ratio so that only water passes through the proportional mixing valve, only LC passes through the proportional mixing valve, or any proportional ratio of water from 0% to 100% relative to LC passes through the proportional mixing valve. A pump such as a centrifugal pump, in which the intake port is connected to the output of an operating proportional mixing valve and the discharge port is connected to a storage tank by a pipe. The pump is connected to a centralized controller that has a variable frequency drive capable of starting or stopping the pump via a signal, and after starting the pump, its flow rate can be controlled from 0% to 100% of its output capacity. • A refractive index sensor is mounted in-line with a storage tank downstream of the pump's discharge port. ○ The window of the refractive index sensor is in fluid contact with the product in the pipe connecting the pump to the storage tank. A controller connected to a power supply, a water supply source operating valve, an LC supply source operating valve, at least one sensor, a variable frequency drive, and a pump. Ready-to-use (RTU) long-acting flame retardants are prepared as follows: 1. Power is supplied to the system, and the controller executes an automated startup routine that checks the connection to each component and the status of each component, and then signals the operator that it is ready. 2. The operator sets initial parameters based on the desired flow rates of the specific flame retardant to be mixed and the RTU flame retardant into the storage tank, and instructs the system to execute. 3. The system then adjusts the initial state of the proportional mixing valve to match the desired mixing ratio for LC. For example, if the mixing ratio for LC is 1 gallon of LC to 2.4 gallons of water, the proportional mixing valve is adjusted to allow 2.4 times more water than LC to pass through the valve. 4. Subsequently, the controller transmits a signal to open the operating valves for the water supply source and the LC supply source. 5. The controller then pressurizes the pump to the desired flow rate input by the operator, which draws water and LC from their respective sources through the valves and pipes of each source into the proportional mixing valve, where they are mixed in the desired ratio. The mixed fluid then moves from the mixing valve through the piping section into the pump. The pump helps to homogenize the mixture before it is delivered to the storage tank or air tanker. 6. As the product is transferred to a storage tank or air tanker, it flows through a refractive index sensor and is measured. The refractive index sensor returns the refractive index value of the mixed RTU product to the controller, and the measured value is compared to a target value. 7. If the measured refractive index of the ready-to-use mixed product being transferred to the storage tank or air tanker is within the tolerance entered by the operator, the system will maintain all settings, continue monitoring the output reading of the refractive index sensor, and operate until the operator stops the system, a preset amount of ready-to-use flame retardant is produced, or the refractive index of the ready-to-use flame retardant being transferred to the storage tank or air tanker falls outside the tolerance. 8. If the controller detects a refractive index value outside the tolerance at any given time, the system will respond accordingly. For example, if the refractive index value detected by the sensor is below the target value, the system will adjust the proportional mixing valve so that more concentrate and less water can pass through the proportional mixing valve. The adjustment will be made in microsteps, and after the adjustment at the proportional mixing valve, sufficient time will be given for the mixed product with the new ratio to reach the refractive index sensor and for the sensor to send the refractive index value back to the controller. If the refractive index of the mixed product returns to within tolerance as a result of the adjustment made to the mixing ratio, the system will maintain those values ​​until either the operator stops the system, a preset amount of ready-to-use mixed flame retardant is produced, or the refractive index of the ready-to-use mixed flame retardant being transferred to the storage tank becomes outside the tolerance. If the refractive index is still outside the tolerance, the system will repeat the process of adjusting the proportional mixing valve in further microsteps and waiting until a new refractive index value is obtained, and will maintain or repeat this process until the refractive index of the product being transferred to the storage tank becomes within tolerance. If the measured refractive index of the ready-to-use mixed product being transferred to the storage tank is within the tolerance entered by the operator, the system maintains all settings, continues to monitor the output reading of the refractive index sensor, and operates until the operator stops the system, a preset amount of ready-to-use flame retardant is produced, or the refractive index of the ready-to-use flame retardant being transferred to the storage tank falls outside the tolerance. [Examples]

[0106] The mixing system includes the following: • Solvent supply source A tank equipped with a float valve or other level sensor that automatically activates to start refilling the tank and maintain a minimum head pressure when the solvent (e.g., water) level falls below a predetermined level, and an operating valve at the outlet of the tank connected by a pipe to one port of an operating proportional mixing valve. ○The operating valve of the solvent tank is connected to a controller that can open and close the valve by transmitting a signal. ·Liquid concentrate source A tank having a liquid concentrate (LC), an operating valve for the tank, and a pipe connecting the valve of the LC container to one port of an operating proportional mixing valve. The LC container's operating valve is connected to a controller that can open and close the valve by transmitting a signal. A pro-market proportional mixing valve having one input port connected to a controller and connected by a pipe to the operating valve of a water supply source, a second input port connected by a pipe to the operating valve of a liquid concentrate (LC) supply source, and an output port. ○The operating proportional mixing valve is adjustable by transmitting a signal and is connected to a controller that can adjust the mixing ratio so that only water passes through the proportional mixing valve, only LC passes through the proportional mixing valve, or any proportional ratio of water from 0% to 100% relative to LC passes through the proportional mixing valve. A pump such as a centrifugal pump, in which the intake port is connected to the output of an operating proportional mixing valve and the discharge port is connected to a storage tank by a pipe. The pump is connected to a centralized controller that has a variable frequency drive capable of starting or stopping the pump via a signal, and after starting the pump, its flow rate can be controlled from 0% to 100% of its output capacity. • A refractive index sensor is mounted in-line with a storage tank downstream of the pump's discharge port. ○ The window of the refractive index sensor is in fluid contact with the product in the pipe connecting the pump to the storage tank. • One or more additional (density in this embodiment) sensors mounted in-line with the storage tank downstream of the pump's discharge section. ○ The sensor is installed in the fluid flow. A controller connected to a power supply, a water supply source operating valve, an LC supply source operating valve, at least one sensor, a variable frequency drive, and a pump. Ready-to-use (RTU) long-acting flame retardants are prepared as follows: 1. Power is supplied to the system, and the controller executes an automated startup routine that checks the connection to each component and the status of each component, and then gives the operator a ready signal. 2. The operator sets initial parameters based on the desired flow rates of the specific flame retardant to be mixed and the RTU flame retardant into the storage tank, and instructs the system to execute. 3. The system then adjusts the initial state of the proportional mixing valve to match the desired mixing ratio for LC. For example, if the mixing ratio for LC is 1 gallon of LC to 2.4 gallons of water, the proportional mixing valve is adjusted to allow 2.4 times more water than LC to pass through the valve. 4. Subsequently, the controller transmits a signal to open the operating valves for the water supply source and the LC supply source. 5. The controller then pressurizes the pump to the desired flow rate input by the operator, which draws water and LC from their respective sources through the valves and pipes of each source into the proportional mixing valve, where they are mixed in the desired ratio. The mixed fluid then moves from the mixing valve through the piping section into the pump. The pump helps to homogenize the mixture before it is delivered to the storage tank. 6. As the product is transferred to the storage tank, it flows through both the refractive index sensor and the density sensor, where they are measured. The refractive index sensor and density sensor return the refractive index and density values ​​of the mixed RTU product to the controller, and the measured values ​​are compared to the target values. 7. If both the measured refractive index and density of the ready-to-use mixed product being transferred to the storage tank are within the tolerances entered by the operator, the system will maintain all settings, continue monitoring the output reading of the refractive index sensor, and operate until the operator stops the system, a preset amount of ready-to-use flame retardant is produced, or the refractive index of the ready-to-use flame retardant being transferred to the storage tank falls outside the tolerance. 8. If the controller detects at any given time that one of the sensors is outside the tolerance, the system responds accordingly. For example, in one embodiment, one or more sensors may be configured to provide a warning or alert for an out-of-tolerance condition but allow the system to continue running without adjusting the proportional mixing valve, and in another embodiment, one or more sensors may be configured to provide an "alarm" condition when an out-of-tolerance condition exists and adjust the proportional mixing valve. The following are additional details of non-limiting examples in which multiple sensors are employed. a. A given (refractive index or density) sensor may be configured as a “warning” sensor or an “alarm / correction” sensor. This designation may apply to all values ​​of a given sensor output that are outside the acceptable range, or some values ​​may be warnings and some values ​​may be alarms and corrections (for example, a warning if the value is outside the acceptable range within X%, and an alarm if the value is outside the acceptable range beyond X%, for example, X may be 1, 5, or 10). b. For example, if density is designated as a warning and refractive index is designated as an alarm / correction, and the refractive index is within tolerance but the density is not, the system will send a warning to the user. The system will continue to run as normal until either the density returns to within specifications, the density enters an alarm / correction state, or mixing is complete. If the refractive index is outside specifications according to the alarm / correction setting, and the controller detects that the refractive index value exceeds the desired target value, the system will adjust the proportional mixing valve so that less concentrate and more water can pass through the proportional mixing valve. c. One measurement indicator is outside the specifications, while others are acceptable. For example, if the controller detects that the refractive index is outside the tolerance but the density is within the tolerance, the system determines whether the refractive index is below or above the desired target value. If the refractive index is above the target value, the system adjusts the proportional mixing valve so that less concentrate and more water can pass through the proportional mixing valve. Similarly, if the density is too high, the system adjusts the proportional mixing valve so that less concentrate and more water can pass through the proportional mixing valve. d. Multiple measurement indicators are outside specifications. If the controller detects that both the refractive index and density values ​​are outside the tolerance, the system determines whether the density and refractive index are below or above the desired target values. If they require adjustment in the same direction (i.e., both are above the target value), the system adjusts the proportional mixing valve so that less concentrate and more water can pass through the proportional mixing valve. Similarly, if both are too low, the system adjusts the proportional mixing valve so that more concentrate and less water can pass through the proportional mixing valve. e. There are cases where an event can occur if one value is below a threshold and another value exceeds a threshold. Although this is unlikely to happen, the system should shut down and the user should be warned. The adjustments described in fa-e are performed in microsteps, ensuring sufficient time for the mixture product with the new ratio to reach the refractive index sensor and for the sensor to return its refractive index value to the controller after the adjustment at the proportional mixing valve. In non-limiting examples, microstep adjustments may include steps that change one or more flow rates by 0.5%, 1%, 5%, or 10%. Non-limiting examples of the amount of time required to allow the new ratio to reach the refractive index sensor may be on the order of milliseconds or fractions of a second, resulting in a substantially instantaneous feedback response in practice. If the adjustment made to the mixing ratio brings the sensor output of the mixture product back within tolerance, the system maintains the sensor output value until either the operator stops the system, a preset amount of ready-to-use flame retardant mixture is produced, or the ready-to-use flame retardant mixture being transferred to the storage tank goes out of tolerance again. If the measured characteristics are still outside the tolerance, the system repeats the process of adjusting the proportional mixing valve in further minute steps and waiting until a new sensor output value is obtained, maintaining or repeating the process until the refractive index of the product being transferred to the storage tank is within the tolerance.

[0107] It should be understood that the above example of providing feedback on the concentration of flame-retardant salts in the RTU flame retardant product using multiple sensors is provided primarily for illustrative purposes. In general, in various embodiments involving multiple sensors, the respective sensor output signals from the multiple sensors may be mathematically combined (e.g., via the controller) to provide a “composite signal” used by the controller to provide a warning or alarm and, otherwise, to adjust or maintain the current state of the proportional mixing valve. In this regard, it should be understood that the controller may have programmable logic functions to adjust or maintain multiple components of the disclosed system (e.g., the proportional mixing valve, the respective operating valves of the solvent tank or LC container, pump speed, etc.) based on the outputs provided by one or more sensors.

[0108] Measuring the state of the diluted product may include measuring at least one of the refractive index, density, viscosity, pH, mass flow rate, conductivity, or selective ion concentration of the final diluted product. In some embodiments, the step of measuring the state of the final diluted product may include measuring the refractive index, density, and viscosity of the final diluted product. The step of modulating the proportional mixing valve may include maintaining a mixing ratio of water to liquid concentrate of about 10:1 to about 0.75:1. The step of modulating the proportional mixing valve may include maintaining a mixing ratio of water to liquid concentrate of about 2:1. The weight percentage of the flame retardant salt compound relative to the total weight of the final diluted product is about 4% to about 30%, preferably about 5% to about 25%, more preferably about 6% to about 23%, and particularly about 7% to about 20%. The step of producing the final diluted product may include producing the final diluted product at a production rate of about 100 gallons / min (gpm) to about 1200 gpm. The final diluted product may have a viscosity of approximately 150 cP to 1500 cP, such as approximately 150 cP to 400 cP, approximately 401 cP to 800 cP, or approximately 801 cP to 1500 cP. The step of introducing the liquid concentrate into the proportional mixing valve may include pumping the liquid concentrate by a mechanical pump. The step of introducing water into the proportional mixing valve may include pumping the water by a pump. Controlling the modulation of the proportional mixing valve may include using the measured state as part of an automatic feedback loop.

[0109] Example of mixed system operation with a single sensor As an example, the final diluted product, i.e., a ready-to-use (RTU) long-acting flame retardant, is prepared by the following steps using a mixing system that includes a water source, a liquid concentrate source, operating valves at the outlets of the water source and the liquid concentrate source, an operating proportional mixing valve, a pump downstream of the proportional mixing valve, a refractive index sensor downstream of the proportional mixing valve for measuring the final diluted product, and a controller that controls the operating valve and pump based on the measurement from the refractive index sensor.

[0110] First, power is supplied to the mixing system, and the mixing system's controller runs an automated startup routine that checks the connections to each component in the mixing system (e.g., sensors, pumps, variable frequency drivers, and valve actuation mechanisms) and the status of each component. After the connections and component statuses are confirmed, the controller signals the operator that the system is ready. The operator sets initial parameters based on the desired flow rates into the storage tanks for the specific flame retardants to be mixed and commands the mixing system to execute.

[0111] The controller adjusts the initial state of the proportional mixing valve to achieve the desired mixing ratio for the liquid concentrate. For example, if the mixing ratio for the liquid concentrate is 1 gallon of liquid concentrate to 2.4 gallons of water, the controller adjusts the configuration of the proportional mixing valve so that 2.4 times more water than liquid concentrate can pass through the valve.

[0112] The controller transmits a signal to open the operating valves for the water supply source and the liquid concentrate supply source.

[0113] The controller pressurizes the downstream pump to the desired production rate according to the rate input by the operator, which draws water and liquid concentrates from their respective sources through the valves and pipes of their respective lines into the proportional mixing valve, where they are mixed in the desired ratio. The mixed fluid moves from the proportional mixing valve through the piping section into the downstream pump. The downstream pump helps to homogenize the mixture of the mixed fluids before supplying the final diluted product to the storage tank.

[0114] As the final diluted product is transferred to the storage tank, it flows through a refractive index sensor and is measured. The refractive index sensor transmits the measured refractive index value of the final diluted product to the controller, where the measured value is compared to a target value.

[0115] If the controller determines that the measured refractive index of the final diluted product is within the target tolerance range entered by the operator, the controller maintains all settings, continues monitoring the output reading of the refractive index sensor, and operates until the operator stops the system, a preset amount of the final diluted product is produced, or the refractive index of the final diluted product being transferred to the storage tank falls outside the tolerance range.

[0116] If the controller detects at any point during the operation of the mixing system that the refractive index of the final diluted product falls outside the target tolerance range, the controller will respond accordingly. For example, if the refractive index measured by the refractive index sensor is below the target tolerance range, the controller will adjust the proportional mixing valve so that more concentrate and less water can pass through the proportional mixing valve. If the refractive index measured by the refractive index sensor is above the target tolerance range, the controller will adjust the proportional mixing valve so that more water and less concentrate can pass through the proportional mixing valve.

[0117] The controller adjusts the proportional mixing valve in microsteps. After each microstep, the controller pauses for a sufficient amount of time for the final diluted product mixed at the new ratio to reach the refractive index sensor, allowing the sensor to measure the final diluted product mixed at the new ratio and transmit the measured refractive index value to the controller.

[0118] If the refractive index of the final diluted product returns to within tolerance by step adjustment of the controller's proportional mixing valve, the controller maintains the new parameters until the system stops operating. The system may stop operating if the operator stops the mixing system, if a preset amount of the final diluted product is produced, or if the refractive index of the final diluted product being transferred to the storage tank falls outside tolerance again.

[0119] If the refractive index of the final diluted product does not return to within tolerance even after adjusting the proportional mixing valve by the controller, the controller repeats the process of adjusting the other proportional mixing valves as described above. The controller repeats the adjustment of the proportional mixing valves until the refractive index of the final diluted product returns to within tolerance. If the controller is unable to return the final diluted product to within tolerance even after adjusting the proportional mixing valves, the controller may stop the operation of the mixing system and send an error code to the operator.

[0120] If the measured refractive index of the final diluted product is within the tolerance entered by the operator, the controller maintains all settings and continues to monitor the refractive index sensor readings. The system operates until the operator stops the system, a preset amount of the final diluted product is produced, or the refractive index of the final diluted product being transferred to the storage tank falls outside the tolerance.

[0121] Example of mixed system operation with two sensors As another example, a ready-to-use (RTU) final dilution product of a long-acting flame retardant is prepared by the following steps using a mixing system that includes a water source, a liquid concentrate source, operating valves at the outlets of the water source and the liquid concentrate source, an operating proportional mixing valve, a pump downstream of the proportional mixing valve, a refractive index sensor downstream of the proportional mixing valve for measuring the final dilution product, a density sensor downstream of the proportional mixing valve for measuring the final dilution product, and a controller that controls the operating valve and pump based on measurements from the refractive index sensor and additional sensors.

[0122] First, power is supplied to the mixing system, and the mixing system's controller runs an automated startup routine that checks the connections to each component in the mixing system (e.g., sensors, pumps, variable frequency drivers, and valve actuation mechanisms) and the status of each component. After the connections and component statuses are confirmed, the controller provides a ready signal to the operator. The operator sets initial parameters based on the desired flow rates into the storage tanks for the specific flame retardants to be mixed and commands the mixing system to execute.

[0123] The controller adjusts the initial state of the proportional mixing valve to achieve the desired mixing ratio for the liquid concentrate. For example, if the mixing ratio for the liquid concentrate is 1 gallon of liquid concentrate to 2.4 gallons of water, the controller adjusts the configuration of the proportional mixing valve so that 2.4 times more water than liquid concentrate can pass through the valve.

[0124] The controller transmits a signal to open the operating valves for the water supply source and the liquid concentrate supply source.

[0125] The controller pressurizes the downstream pump to the desired production rate according to the rate input by the operator, which draws water and liquid concentrates from their respective sources through valves and pipes in their respective upstream lines into a proportional mixing valve, where they are mixed in the desired ratio. The mixed fluid then moves from the proportional mixing valve through a pipe section into the downstream pump. The downstream pump helps to homogenize the mixture of the mixed fluids before delivering the final diluted product to the storage tank.

[0126] As the final diluted product is transferred to the storage tank, it flows through a refractive index sensor and a density sensor, where it is measured. The refractive index sensor and density sensor transmit the measured sensor values ​​of the final diluted product to the controller, where the measured values ​​are compared to a target value.

[0127] If the controller determines that the measured refractive index and density of the final diluted product are within the target tolerance range entered by the operator, the controller maintains all settings and continues operating the mixing system until it stops. The controller continues to monitor the output readings of the refractive index sensor and density sensor and operates accordingly.

[0128] If the controller determines at any given time that one of the sensors is outside the target tolerance range, the controller responds in one of several ways described below.

[0129] The refractive index sensor and density sensor are configured as warning sensors and / or alarm and correction sensors. In some examples, one or both sensors are designated as both warning and alarm / correction sensors, with sensor readings that are close to but outside the target tolerance range generating a warning, and sensor readings that are further outside the target tolerance range generating an alarm / correction action. In some examples, one sensor acts as a warning sensor and the other as an alarm / correction sensor.

[0130] For example, if a density sensor is designated as a warning sensor and a refractive index sensor is designated as an alarm / correction sensor, the controller may send a warning to the operator if the measured refractive index is within tolerance but the measured density is not, but will not change any parameters of the mixing system. The mixing system will continue to run with the same parameters until the density returns to within specifications, the density enters an alarm / correction state, or the mixing system terminates operation (e.g., produces a specified amount of final diluted product). If the controller determines that the measured refractive index is outside the target tolerance range, the controller adjusts the proportional mixing valve accordingly, regardless of whether the density is within that tolerance range. If the controller detects that both the measured refractive index and density are outside their target tolerance ranges, the controller determines whether the density and refractive index are below or above the desired target value. If both the density and refractive index are above their target tolerance ranges, the controller adjusts the proportional mixing valve so that less concentrate and more water can pass through it. If both density and refractive index are below their target tolerances, the controller adjusts the proportional mixing valve to allow more concentrate and less water to pass through. If the controller detects that one sensor reading exceeds its target tolerance and the other sensor reading is below its target tolerance, the controller may stop the mixing system and warn the operator.

[0131] The controller performs the above adjustments in minute steps, and after each step adjustment, it ensures sufficient time for the final diluted product, mixed at the new ratio, to reach the refractive index and density sensors and transmit the measured refractive index and density to the controller. If the adjustments made to the mixing ratio bring the sensor output of the final diluted product back within tolerance, the controller maintains the parameters until either the operator stops the system, a preset amount of the final diluted product is produced, or the final diluted product being transferred to the storage tank is again outside tolerance. If the measured refractive index or density is still outside tolerance, the controller repeats the step adjustment process to the proportional mixing valve until the refractive index and / or density of the final diluted product being transferred to the storage tank is within tolerance.

[0132] Figure 3 shows a method 300 for providing a ready-to-use (RTU) flame retardant product for use in aircraft, the RTU flame retardant product containing at least one flame retardant compound relating to this technology. Method 300 may include blocks 310-330.

[0133] Block 310 may include step 310A: a step of forming an RTU flame retardant product by flowing water from a solvent tank through a single automated proportional mixing valve and operating at least one pump to flow a liquid concentrate (LC) flame retardant containing at least one flame retardant compound from a liquid concentrate (LC) container, wherein the LC head pressure of the LC flame retardant in the LC container changes during step 310A, and the RTU flame retardant product is pumped at a flow rate in the range of 200 gallons / min to 1000 gallons / min through at least one conduit coupled between the single automated proportional mixing valve and a flow meter associated with the aircraft.

[0134] The LC flame retardant may have a viscosity in the range of 1500 cP to 3000 cP. At least one flame retardant compound may contain at least one of magnesium chloride, ammonium phosphate, or polyphosphate. During block 310, the solvent head pressure of the solvent in the solvent tank can be maintained at a substantially constant level.

[0135] Method 300 may include, prior to block 310, a step of receiving a first user input via a user interface. The first user input may relate to a target mixing ratio of water or other suitable solvent and LC flame retardant to form the RTU flame retardant product. Method 300 may further include, prior to block 310, a step of adjusting the initial state of a single automated proportional mixing valve, at least to some extent based on the target mixing ratio, so that at least one flow variable for each of the LC flame retardant and water is initialized by the single automated proportional mixing valve.

[0136] A solvent tank may include a first operating valve at the outlet of the solvent tank. An LC container may include a second operating valve at the outlet of the LC container. Method 300 further includes, before block 310, the step of automatically opening the first and second operating valves after adjusting the initial state of a single automated proportional mixing valve.

[0137] Method 300 may further include, prior to block 310, a second user input relating to a target flow rate for the RTU flame retardant product, received via a user interface. Block 310 may then further include the step of operating at least one pump to draw water and LC flame retardant through a single automated proportional mixing valve by gradually increasing the flow rate of the RTU flame retardant product to a target flow rate.

[0138] Method 300 may further include, prior to block 310, a third user input regarding a target refractive index range for the RTU flame retardant product, received via a user interface.

[0139] Block 320 may include the step of automatically and repeatedly measuring the inline refractive index of the RTU flame retardant product by an inline refractometer placed in at least one conduit between a single automated proportional mixing valve and an aircraft-associated flow meter, as the RTU flame retardant product is pumped through at least one conduit to generate multiple refractive index measurements for the RTU flame retardant product.

[0140] Block 320 may further include the step of storing a digital record of at least some of a plurality of refractive index measurements.

[0141] Block 320 may further include the step of automatically and repeatedly measuring the inline refractive index of the RTU flame retardant product by an inline refractometer placed in at least one conduit between a single automated proportional mixing valve and an aircraft-associated flow meter, as the RTU flame retardant product is pumped through at least one conduit, in order to generate multiple refractive index measurements for the RTU flame retardant product.

[0142] Block 320 may further include the step of automatically and repeatedly measuring the inline density of the RTU flame retardant product by an aircraft-associated flow meter as the RTU flame retardant product is pumped through at least one conduit, in order to generate multiple density measurements for the RTU flame retardant product.

[0143] Block 330 may include step 330C, which automatically adjusts or maintains at least one flow parameter for each of the LC flame retardant and water by the operation of a single automated proportional mixing valve, based at least to some extent on a plurality of refractive index measurements generated in step 320B, in order to achieve a target refractive index of the RTU flame retardant product in the range of 8 to 30 for any 10440VP scale.

[0144] In block 330, the target weight percentage of at least one flame retardant compound in the RTU flame retardant product may be in the range of 8% to 12%. The target refractive index of the RTU flame retardant product may be in the range of 8.5 to 20.0 on an arbitrary scale of 10440VP.

[0145] In block 330, step 330C may be performed after the flow rate of the RTU flame retardant product reaches the target flow rate.

[0146] In block 330, step 330C1 may further include, in a first time, comparing a first refractive index measurement among a plurality of refractive index measurements generated in B) with a range for a target refractive index of the RTU flame retardant product.

[0147] In block 330, step 330C may further include step 330C2, in which a first refractive index measurement of the RTU flame retardant product is within the range of the target refractive index of the RTU flame retardant product, maintaining at least one flow variable for each of the LC flame retardant and water by a single automated proportional mixing valve.

[0148] In block 330, step 330C may further include step 330C3, which adjusts at least one flow variable for each of the LC flame retardant and water by a single automated proportional mixing valve if the first refractive index measurement of the RTU flame retardant product is not within the range for the target refractive index of the RTU flame retardant product. If the first refractive index measurement of the RTU flame retardant product is not within the range for the target refractive index of the RTU flame retardant product, step 330C3 may include operating the single automated proportional mixing valve to adjust at least one flow variable for each of the LC flame retardant and water such that the in-line refractive index of the RTU flame retardant product changes by about 0.1 for any scale of 10440VP in step 320B.

[0149] In block 330, step 330C may further include step 330C4, which stops at least one pump in A) if a fourth user input relating to stopping the operation of at least one pump is received via the user interface. Step 330C may further include step 330C5, which stops at least one pump in step 310A, if a fifth user input relating to a preset amount of RTU flame retardant product is received via the user interface and the amount of RTU flame retardant product being pumped through at least one conduit is equal to, approximately equal to or greater than, a preset amount of RTU flame retardant product.

[0150] In block 330, step 330C may further include step 330C6, which repeats steps 330C1 and 330C2 or step 330C3 using a second refractive index measurement from a plurality of refractive index measurements in a second time.

[0151] In block 330, step 330C6 may further include step 330C6a, which involves waiting for a predetermined period of time following step 330C3. After waiting for the predetermined period, step 330C6 may further include step 330C6b, which involves repeating steps 330C1 and 330C2 or 330C3 in a second time period using a second refractive index measurement from among a plurality of refractive index measurements.

[0152] In block 330, step 330C may further include the step of automatically adjusting or maintaining at least one flow parameter for each of the LC flame retardant and water by a single automated proportional mixing valve, based at least to some extent on a plurality of refractive index measurements generated in step 320B1 and a plurality of density measurements generated in step 330B2, in order to achieve a target refractive index of the RTU flame retardant product in the range of 8 to 30 for any 10440VP scale.

[0153] Figure 4 shows a method 400 for providing a ready-to-use (RTU) flame retardant product containing at least one flame retardant compound. Method 400 may comprise blocks 410-430.

[0154] Block 410 may include step 410A, which involves forming an RTU flame retardant product by producing a mixture of water and a liquid concentrate (LC) flame retardant containing at least one flame retardant compound. The LC flame retardant has a viscosity in the range of 1500 centipoise (cP) to 3000 cP.

[0155] Block 420 may include step 420B of measuring at least one parameter representing the concentration of at least one flame retardant compound in the mixture.

[0156] Block 430 may include step 430C, which automatically adjusts at least one flow parameter for each of the LC flame retardant and water, based at least to some extent on step 420B, to achieve a target weight percentage of at least one flame retardant compound in the RTU flame retardant product ranging from 8% to 12%, and a flow rate for the RTU flame retardant product ranging from 200 gallons / min to 1000 gallons / min.

[0157] Figure 5 shows a method 500 for providing a ready-to-use (RTU) flame retardant product containing at least one flame retardant compound. Method 500 may comprise blocks 510-530.

[0158] Block 510 may include step 510A, which involves forming an RTU flame retardant product by producing a mixture of water and a liquid concentrate (LC) flame retardant containing at least one flame retardant compound. The LC flame retardant has a viscosity in the range of 1500 centipoise (cP) to 3000 cP, and the head pressure of the LC flame retardant changes over time.

[0159] Block 520 may include step 520B of measuring the refractive index of the mixture.

[0160] Block 530 may include step 530C, which, based at least to some extent on step 520B, automatically adjusts at least one flow parameter for each of the LC flame retardant and water to achieve a target refractive index in the range of 8.5 to 20.0 for any 10440VP scale and a flow rate for the RTU flame retardant product in the range of 200 gallons / min to 1000 gallons / min.

[0161] conclusion While various embodiments of the invention have been described and explained herein, those skilled in the art will immediately conceive of various other means and / or structures to perform the functions described herein and / or to obtain one or more of the results and / or advantageous effects described herein, and each of such modifications and / or variations will be considered to be within the scope of the embodiments of the invention described herein. More generally, those skilled in the art will immediately understand that all parameters, dimensions, materials and configurations described herein are illustrative, and that actual parameters, dimensions, materials and / or configurations may depend on the specific use in which the teachings of the invention are used. Those skilled in the art will be able to recognize and confirm numerous equivalents to the specific embodiments of the invention described herein by means of routine experimentation alone. Therefore, it should be understood that the above embodiments are presented merely as examples, and that embodiments of the invention may be implemented in ways other than those specifically described and claimed within the scope of the appended claims and their equivalents. The embodiments of the invention of this disclosure are directed to each individual feature, system, article, material, kit and / or method described herein. Furthermore, any two or more combinations of such features, systems, articles, materials, kits and / or methods are included within the scope of the inventions of this disclosure, provided that the features, systems, articles, materials, kits and / or methods are not mutually inconsistent.

[0162] Furthermore, various inventive concepts may be implemented as one or more methods, and examples of such implementations have been given. The actions performed as part of a method may be ordered in any appropriate manner. Thus, even if the actions are shown as sequential actions in the explanatory embodiments, embodiments may be constructed in which the actions are performed in a different order than described, which may include performing some of the actions simultaneously.

[0163] All definitions set forth herein and used herein should be understood to take precedence over dictionary definitions, definitions in documents incorporated by reference, and / or the ordinary meanings of the terms defined.

[0164] In the specification and claims, the indefinite articles "a" and "an" used herein should be understood to mean "at least one" unless the opposite is explicitly indicated.

[0165] The terms "and / or" as used herein in the specification and claims should be understood to mean "either or both" of the elements thus interconnected, that is, elements that exist interconnected in some examples and separately in others. Multiple elements listed with "and / or" should be interpreted in the same manner, that is, "one or more" of the elements thus interconnected. Other elements may optionally exist in addition to those specifically identified by the "and / or" clause, whether or not they are related to those specifically identified elements. Thus, as a non-restrictive example, when used in conjunction with open-ended language such as "comprising," a reference to "A and / or B" may, in some embodiments, mean only A (optionally including elements other than B), in other embodiments, only B (optionally including elements other than A), and in yet another embodiment, both A and B (optionally including other elements), and so on.

[0166] As used herein in the specification and claims, “or” should be understood to have the same meaning as “and / or” as defined above. For example, when separating items in an enumeration, “or” or “and / or” should be interpreted as inclusive, that is, including not just at least one inclusion, but two or more of the multiple or enumerated elements and optionally additional unenumerated items. Only terms that explicitly indicate the opposite, such as “one of” or “solely one of” or, when used in claims, “consisting of,” refer to the inclusion of just one element of the multiple or enumerated elements. In general, the term “or” as used herein should be interpreted only as indicating an exclusive substitution (i.e., “one or the other, but not both”) when followed by terms of exclusivity such as “either one,” “one of,” “one of” or “solely one.” “Consisting essentially of” when used in claims has its usual meaning as it is used in the field of patent law.

[0167] As used herein in the specification and claims, the phrase “at least one (one kind)” in relation to an enumeration of one or more elements means at least one element selected from any one or more elements in the enumeration of elements, and does not necessarily include at least one of each and all elements specifically enumerated in the enumeration of elements, nor does it exclude any combination of elements in the enumeration of elements. This definition also allows for the optional presence of elements other than those specifically identified in the enumeration of elements to which the phrase “at least one” refers, whether related to or unrelated to the specifically identified elements. Therefore, as a non-restrictive example, "at least one of A and B" (or synonymously, "at least one of A or B" or synonymously, "at least one of A and / or B") may mean, in one embodiment, at least one that optionally includes two or more A's (and optionally includes elements other than B) without the presence of B; in another embodiment, at least one that optionally includes two or more B's (and optionally includes elements other than A) without the presence of A; and in yet another embodiment, at least one that optionally includes two or more A's and at least one that optionally includes two or more B's (and optionally includes other elements).

[0168] In the claims and the above specification, all transitional phrases such as “comprising,” “including,” “carrying,” “having,” “containing,” “involving,” “holding,” and “composed of” should be understood as open-ended, meaning they include but are not limited to. As explained in Section 2111.03 of the U.S. Patent and Trademark Office Manual of Patent Examination Procedure, only the transitional phrases “consisting of” and “consisting essentially of” are closed or semi-closed transitional phrases, respectively.

Claims

1. A mixing plant that provides ready-to-use (RTU) flame retardant products containing at least one flame retardant compound for use in aircraft, A water tank that holds water, A liquid concentrate (LC) container for holding a liquid concentrate (LC) flame retardant containing at least one flame retardant compound, wherein the LC head pressure of the LC flame retardant in the LC container changes as the LC flame retardant is consumed to provide the RTU flame retardant product. A single automated proportional mixing valve is fluidly coupled to the water tank and the LC container in order to form the RTU flame retardant product by mixing the water and the LC flame retardant. To transport the RTU flame retardant product from the single automated proportional mixing valve, at least one conduit is fluid-coupled to the single automated proportional mixing valve and the flow meter, To pump the RTU flame retardant product through the at least one conduit, at least one pump is fluidly coupled to the at least one conduit, To measure the in-line refractive index of the RTU flame retardant product in the at least one conduit, an in-line refractometer is positioned in the at least one conduit between the single automated proportional mixing valve and the flow meter so as to be in fluid contact with the RTU flame retardant product, At least one controller, which is communicated to the inline refractometer and the single automated proportional mixing valve, and which automatically adjusts at least one flow variable for the LC flame retardant and the water, respectively, by the single automated proportional mixing valve, based at least to some extent on the inline refractive index measured by the inline refractometer, in order to achieve a target refractive index of the RTU flame retardant product in the range of 10 to 30 for an arbitrary scale of 10440 VP, A mixing plant equipped with the following features.

2. The mixing plant according to claim 1, wherein the water tank is equipped with a water level sensor to automatically replenish the water tank with additional water as the water is consumed and provides the RTU flame retardant product, in order to maintain a substantially constant water head pressure at the outlet of the water tank.

3. A first operating valve coupled to the outlet of the water tank and connected to the at least one controller, the first operating valve responding to a first signal output by the at least one controller to open and close the first operating valve, A second operating valve coupled to the outlet of the LC container and connected to the at least one controller, the second operating valve responding to a second signal output by the at least one controller to open and close the second operating valve, The mixing plant according to claim 1, further comprising:

4. A first operating valve coupled to the outlet of the water tank and connected to the at least one controller, the first operating valve responding to a first signal output by the at least one controller to open and close the first operating valve, A second operating valve coupled to the outlet of the LC container and connected to the at least one controller, the second operating valve responding to a second signal output by the at least one controller to open and close the second operating valve, The mixing plant according to claim 2, further comprising:

5. The mixing plant according to claim 2, wherein the at least one pump is communicated to the at least one controller and controls the flow rate of the at least one pump in response to the at least one pump control signal output by the at least one controller.

6. The mixing plant according to claim 3, wherein the at least one pump is communicated to the at least one controller and controls the flow rate of the at least one pump in response to the at least one pump control signal output by the at least one controller.

7. The flow meter further comprises the aforementioned flow meter, The mixing plant according to claim 1, wherein the at least one controller is communicated to the inline refractometer, the flow meter and the single automated proportional mixing valve, and the single automated proportional mixing valve automatically adjusts the at least one flow variable for the LC flame retardant and the water, respectively, based at least to some extent on the inline refractive index measured by the inline refractometer and the inline density of the RTU flame retardant product measured by the flow meter, in order to achieve a target refractive index of the RTU flame retardant product in the range of 8 to 30 for an arbitrary scale of 10440VP.

8. The flow meter further comprises the aforementioned flow meter, The mixing plant according to claim 2, wherein the at least one controller is communicated to the inline refractometer, the flow meter and the single automated proportional mixing valve, and the single automated proportional mixing valve automatically adjusts the at least one flow variable for the LC flame retardant and the water, respectively, based at least to some extent on the inline refractive index measured by the inline refractometer and the inline density of the RTU flame retardant product measured by the flow meter, in order to achieve a target refractive index of the RTU flame retardant product in the range of 8 to 30 for any 10440VP scale.

9. The flow meter further comprises the aforementioned flow meter, The mixing plant according to claim 3, wherein the at least one controller is communicated to the inline refractometer, the flow meter and the single automated proportional mixing valve, and the single automated proportional mixing valve automatically adjusts the at least one flow variable for the LC flame retardant and the water, respectively, based at least to some extent on the inline refractive index measured by the inline refractometer and the inline density of the RTU flame retardant product measured by the flow meter, in order to achieve a target refractive index of the RTU flame retardant product in the range of 8 to 30 for any 10440VP scale.

10. The flow meter further comprises the aforementioned flow meter, The mixing plant according to claim 5, wherein the at least one controller is communicated to the inline refractometer, the flow meter and the single automated proportional mixing valve, and the single automated proportional mixing valve automatically adjusts the at least one flow variable for the LC flame retardant and the water, respectively, based at least to some extent on the inline refractive index measured by the inline refractometer and the inline density of the RTU flame retardant product measured by the flow meter, in order to achieve a target refractive index of the RTU flame retardant product in the range of 8 to 30 for an arbitrary scale of 10440VP.

11. A method for providing a ready-to-use (RTU) flame retardant product containing at least one flame retardant compound, A) A step of forming the RTU flame retardant product by producing a mixture of water and a liquid concentrate (LC) flame retardant containing at least one flame retardant compound, wherein the LC flame retardant has a viscosity in the range of 1500 centipoise (cP) to 3000 cP. B) A step of measuring at least one parameter representing the concentration of at least one flame retardant compound in the mixture, C) Based at least to some extent on B) above, at least one flow parameter for each of the LC flame retardant and the water, A target weight percentage of 8% to 12% of the at least one flame retardant compound in the RTU flame retardant product is achieved. Achieve a flow rate for the RTU flame retardant product in the range of 200 gallons / min to 1000 gallons / min. Steps to automatically adjust in this way, A method for providing this.

12. A method for providing a ready-to-use (RTU) flame retardant product containing at least one flame retardant compound, A) A step of forming the RTU flame retardant product by producing a mixture of water and a liquid concentrate (LC) flame retardant containing at least one flame retardant compound, The LC flame retardant has a viscosity in the range of 1500 centipoise (cP) to 3000 cP. The head pressure of the LC flame retardant changes over time. Steps and B) A step of measuring the refractive index of the mixture, C) Based at least to some extent on B) above, at least one flow parameter for each of the LC flame retardant and the water, A target refractive index in the range of 8.5 to 20.0 is achieved for any scale of 10440 VP. Achieve a flow rate for the RTU flame retardant product in the range of 200 gallons / min to 1000 gallons / min. Steps to automatically adjust in this way, A method for providing this.

13. A method for providing a ready-to-use (RTU) flame retardant product for use in aircraft, wherein the RTU flame retardant product contains at least one flame retardant compound, and the method is: A) A step of forming the RTU flame retardant product by flowing water from a water tank through a single automated proportional mixing valve and operating at least one pump to flow a liquid concentrate (LC) flame retardant containing at least one flame retardant compound from a liquid concentrate (LC) container, The LC head pressure of the LC flame retardant in the LC container changes during A), The RTU flame retardant product is pumped at a flow rate in the range of 200 gallons / min to 1000 gallons / min through at least one conduit coupled between the single automated proportional mixing valve and the flow meter associated with the aircraft, step, B) The steps of automatically and repeatedly measuring the inline refractive index of the RTU flame retardant product by an inline refractometer located in the at least one conduit between the single automated proportional mixing valve and the flow meter associated with the aircraft, as the RTU flame retardant product is pumped through the at least one conduit to generate a plurality of refractive index measurements for the RTU flame retardant product, C) In order to achieve a target refractive index of the RTU flame retardant product in the range of 8 to 30 for any 10440VP scale, the steps of automatically adjusting or maintaining at least one flow variable for each of the LC flame retardant and the water by the operation of the single automated proportional mixing valve, based at least to some extent on the plurality of refractive index measurements generated in B), A method for providing this.

14. The method according to claim 13, wherein the LC flame retardant has a viscosity in the range of 1500 centipoise (cP) to 3000 cP.

15. The method according to claim 13, wherein, in C) above, the target weight percentage of the at least one flame retardant compound in the RTU flame retardant product is in the range of 8% to 12%.

16. The method according to claim 13, wherein, in C) above, the target refractive index of the RTU flame retardant product is in the range of 8.5 to 20.0 with respect to the arbitrary scale of 10440VP.

17. The method according to claim 15, wherein, in C) above, the target refractive index of the RTU flame retardant product is in the range of 8.5 to 20.0 with respect to the arbitrary scale of 10440VP.

18. The method according to claim 13, wherein the at least one flame retardant compound comprises at least one of magnesium chloride, ammonium phosphate, or polyphosphate.

19. The method according to claim 14, wherein the at least one flame retardant compound comprises at least one of magnesium chloride, ammonium phosphate, or polyphosphate.

20. The method according to claim 15, wherein the at least one flame retardant compound includes at least one of magnesium chloride, ammonium phosphate, or polyphosphate.

21. The method according to claim 16, wherein the at least one flame retardant compound comprises at least one of magnesium chloride, ammonium phosphate, or polyphosphate.

22. The method according to claim 17, wherein the at least one flame retardant compound comprises at least one of magnesium chloride, ammonium phosphate, or polyphosphate.

23. The method according to claim 13, wherein A) further comprises the step of maintaining the water head pressure of the water in the water tank substantially constant during A).

24. The method according to claim 14, wherein A) further comprises the step of maintaining the water head pressure of the water in the water tank substantially constant during A).

25. The method according to claim 15, wherein A) further comprises the step of maintaining the water head pressure of the water in the water tank substantially constant during A).

26. The method according to claim 16, wherein A) further comprises the step of maintaining the water head pressure of the water in the water tank substantially constant during A).

27. The method according to claim 17, wherein A) further comprises the step of maintaining the water head pressure of the water in the water tank substantially constant during A).

28. The method according to claim 18, wherein A) further comprises the step of maintaining the water head pressure of the water in the water tank substantially constant during A).

29. The method according to claim 13, further comprising the step of storing a digital record of at least some of the plurality of refractive index measurements generated in B) above.

30. The method according to claim 14, further comprising the step of storing a digital record of at least some of the plurality of refractive index measurements generated in B) above.

31. The method according to claim 15, further comprising the step of storing a digital record of at least some of the plurality of refractive index measurements generated in B) above.

32. The method according to claim 16, further comprising the step of storing a digital record of at least some of the plurality of refractive index measurements generated in B) above.

33. The method according to claim 17, further comprising the step of storing a digital record of at least some of the plurality of refractive index measurements generated in B) above.

34. The method according to claim 18, further comprising the step of storing a digital record of at least some of the plurality of refractive index measurements generated in B) above.

35. The method according to claim 23, further comprising the step of storing a digital record of at least some of the plurality of refractive index measurements generated in B) above.

36. Before A) above, The steps include receiving a first user input via a user interface regarding a target mixing ratio of the water and the LC flame retardant that form the RTU flame retardant product, The steps include adjusting the initial state of the single automated proportional mixing valve based at least to some extent on the target mixing ratio, so that the single automated proportional mixing valve sets the flow parameters of at least one flow parameter for each of the LC flame retardant and the water, respectively, The method according to claim 13, further comprising:

37. Before A) above, The steps include receiving a first user input via a user interface regarding a target mixing ratio of the water and the LC flame retardant that form the RTU flame retardant product, The steps include adjusting the initial state of the single automated proportional mixing valve based at least to some extent on the target mixing ratio, so that the single automated proportional mixing valve sets the flow parameters of at least one flow parameter for each of the LC flame retardant and the water, respectively, The method according to claim 14, further comprising:

38. Before A) above, The steps include receiving a first user input via a user interface regarding a target mixing ratio of the water and the LC flame retardant that form the RTU flame retardant product, The steps include adjusting the initial state of the single automated proportional mixing valve based at least to some extent on the target mixing ratio, so that the single automated proportional mixing valve sets the flow parameters of at least one flow parameter for each of the LC flame retardant and the water, respectively, The method according to claim 15, further comprising:

39. Before A) above, The steps include receiving a first user input via a user interface regarding a target mixing ratio of the water and the LC flame retardant that form the RTU flame retardant product, The steps include adjusting the initial state of the single automated proportional mixing valve based at least to some extent on the target mixing ratio, so that the single automated proportional mixing valve sets the flow parameters of at least one flow parameter for each of the LC flame retardant and the water, respectively, The method according to claim 16, further comprising:

40. Before A) above, The steps include receiving a first user input via a user interface regarding a target mixing ratio of the water and the LC flame retardant that form the RTU flame retardant product, The steps include adjusting the initial state of the single automated proportional mixing valve based at least to some extent on the target mixing ratio, so that the single automated proportional mixing valve sets the flow parameters of at least one flow parameter for each of the LC flame retardant and the water, respectively, The method according to claim 17, further comprising:

41. Before A) above, The steps include receiving a first user input via a user interface regarding a target mixing ratio of the water and the LC flame retardant that form the RTU flame retardant product, The steps include adjusting the initial state of the single automated proportional mixing valve based at least to some extent on the target mixing ratio, so that the single automated proportional mixing valve sets the flow parameters of at least one flow parameter for each of the LC flame retardant and the water, respectively, The method according to claim 18, further comprising:

42. Before A) above, The steps include receiving a first user input via a user interface regarding a target mixing ratio of the water and the LC flame retardant that form the RTU flame retardant product, The steps include adjusting the initial state of the single automated proportional mixing valve based at least to some extent on the target mixing ratio, so that the single automated proportional mixing valve sets the flow parameters of at least one flow parameter for each of the LC flame retardant and the water, respectively, The method according to claim 23, further comprising:

43. Before A) above, The steps include receiving a first user input via a user interface regarding a target mixing ratio of the water and the LC flame retardant that form the RTU flame retardant product, The steps include adjusting the initial state of the single automated proportional mixing valve based at least to some extent on the target mixing ratio, so that the single automated proportional mixing valve sets the flow parameters of at least one flow parameter for each of the LC flame retardant and the water, respectively, The method according to claim 29, further comprising:

44. The water tank includes a first operating valve at the outlet of the water tank, and the LC container includes a second operating valve at the outlet of the LC container, and the method, before A), After adjusting the initial state of the single automated proportional mixing valve, the first operating valve and the second operating valve are automatically opened. The method according to claim 36, further comprising:

45. The water tank includes a first operating valve at the outlet of the water tank, and the LC container includes a second operating valve at the outlet of the LC container, and the method, before A), After adjusting the initial state of the single automated proportional mixing valve, the first operating valve and the second operating valve are automatically opened. The method according to claim 37, further comprising:

46. The water tank includes a first operating valve at the outlet of the water tank, and the LC container includes a second operating valve at the outlet of the LC container, and the method, before A), After adjusting the initial state of the single automated proportional mixing valve, the first operating valve and the second operating valve are automatically opened. The method according to claim 38, further comprising:

47. The water tank includes a first operating valve at the outlet of the water tank, and the LC container includes a second operating valve at the outlet of the LC container, and the method, before A), After adjusting the initial state of the single automated proportional mixing valve, the first operating valve and the second operating valve are automatically opened. The method according to claim 39, further comprising:

48. The water tank includes a first operating valve at the outlet of the water tank, and the LC container includes a second operating valve at the outlet of the LC container, and the method, before A), After adjusting the initial state of the single automated proportional mixing valve, the first operating valve and the second operating valve are automatically opened. The method according to claim 40, further comprising:

49. The water tank includes a first operating valve at the outlet of the water tank, and the LC container includes a second operating valve at the outlet of the LC container, and the method, before A), After adjusting the initial state of the single automated proportional mixing valve, the first operating valve and the second operating valve are automatically opened. The method according to claim 41, further comprising:

50. The water tank includes a first operating valve at the outlet of the water tank, and the LC container includes a second operating valve at the outlet of the LC container, and the method, before A), After adjusting the initial state of the single automated proportional mixing valve, the first operating valve and the second operating valve are automatically opened. The method according to claim 42, further comprising:

51. The water tank includes a first operating valve at the outlet of the water tank, and the LC container includes a second operating valve at the outlet of the LC container, and the method, before A), After adjusting the initial state of the single automated proportional mixing valve, the first operating valve and the second operating valve are automatically opened. The method according to claim 43, further comprising:

52. Prior to A) above, the user receives a second user input regarding the target flow rate of the RTU flame retardant product via the user interface. In A) above, the step of operating the at least one pump to draw out the water and the LC flame retardant through the single automated proportional mixing valve by gradually increasing the flow rate of the RTU flame retardant product to the target flow rate, The method according to claim 36, further comprising:

53. Prior to A) above, the user receives a second user input regarding the target flow rate of the RTU flame retardant product via the user interface. In A) above, the step of operating the at least one pump to draw out the water and the LC flame retardant through the single automated proportional mixing valve by gradually increasing the flow rate of the RTU flame retardant product to the target flow rate, The method according to claim 37, further comprising:

54. Prior to A) above, the user receives a second user input regarding the target flow rate of the RTU flame retardant product via the user interface. In A) above, the step of operating the at least one pump to draw out the water and the LC flame retardant through the single automated proportional mixing valve by gradually increasing the flow rate of the RTU flame retardant product to the target flow rate, The method according to claim 38, further comprising:

55. Prior to A) above, the user receives a second user input regarding the target flow rate of the RTU flame retardant product via the user interface. In A) above, the step of operating the at least one pump to draw out the water and the LC flame retardant through the single automated proportional mixing valve by gradually increasing the flow rate of the RTU flame retardant product to the target flow rate, The method according to claim 39, further comprising:

56. Prior to A) above, the user receives a second user input regarding the target flow rate of the RTU flame retardant product via the user interface. In A) above, the step of operating the at least one pump to draw out the water and the LC flame retardant through the single automated proportional mixing valve by gradually increasing the flow rate of the RTU flame retardant product to the target flow rate, The method according to claim 40, further comprising:

57. Prior to A) above, the user receives a second user input regarding the target flow rate of the RTU flame retardant product via the user interface. In A) above, the step of operating the at least one pump to draw out the water and the LC flame retardant through the single automated proportional mixing valve by gradually increasing the flow rate of the RTU flame retardant product to the target flow rate, The method according to claim 41, further comprising:

58. Prior to A) above, the user receives a second user input regarding the target flow rate of the RTU flame retardant product via the user interface. In A) above, the step of operating the at least one pump to draw out the water and the LC flame retardant through the single automated proportional mixing valve by gradually increasing the flow rate of the RTU flame retardant product to the target flow rate, The method according to claim 42, further comprising:

59. Prior to A) above, the user receives a second user input regarding the target flow rate of the RTU flame retardant product via the user interface. In A) above, the step of operating the at least one pump to draw out the water and the LC flame retardant through the single automated proportional mixing valve by gradually increasing the flow rate of the RTU flame retardant product to the target flow rate, The method according to claim 43, further comprising:

60. Prior to A) above, the user receives a second user input regarding the target flow rate of the RTU flame retardant product via the user interface. In A) above, the step of operating the at least one pump to draw out the water and the LC flame retardant through the single automated proportional mixing valve by gradually increasing the flow rate of the RTU flame retardant product to the target flow rate, The method according to claim 44, further comprising:

61. Prior to A) above, the user receives a second user input regarding the target flow rate of the RTU flame retardant product via the user interface. In A) above, the step of operating the at least one pump to draw out the water and the LC flame retardant through the single automated proportional mixing valve by gradually increasing the flow rate of the RTU flame retardant product to the target flow rate, The method according to claim 45, further comprising:

62. Prior to A) above, the user receives a second user input regarding the target flow rate of the RTU flame retardant product via the user interface. In A) above, the step of operating the at least one pump to draw out the water and the LC flame retardant through the single automated proportional mixing valve by gradually increasing the flow rate of the RTU flame retardant product to the target flow rate, The method according to claim 46, further comprising:

63. Prior to A) above, the user receives a second user input regarding the target flow rate of the RTU flame retardant product via the user interface. In A) above, the step of operating the at least one pump to draw out the water and the LC flame retardant through the single automated proportional mixing valve by gradually increasing the flow rate of the RTU flame retardant product to the target flow rate, The method according to claim 47, further comprising:

64. Prior to A) above, the user receives a second user input regarding the target flow rate of the RTU flame retardant product via the user interface. In A) above, the step of operating the at least one pump to draw out the water and the LC flame retardant through the single automated proportional mixing valve by gradually increasing the flow rate of the RTU flame retardant product to the target flow rate, The method according to claim 48, further comprising:

65. Prior to A) above, the user receives a second user input regarding the target flow rate of the RTU flame retardant product via the user interface. In A) above, the step of operating the at least one pump to draw out the water and the LC flame retardant through the single automated proportional mixing valve by gradually increasing the flow rate of the RTU flame retardant product to the target flow rate, The method according to claim 49, further comprising:

66. The method according to claim 36, wherein C) is performed after the flow rate of the RTU flame retardant product reaches the target flow rate.

67. The method according to claim 44, wherein C) is performed after the flow rate of the RTU flame retardant product reaches the target flow rate.

68. The method according to claim 52, wherein C) is performed after the flow rate of the RTU flame retardant product reaches the target flow rate.

69. Before A) above, A third user input regarding the range of the target refractive index for the RTU flame retardant product is received via the user interface. The method according to claim 36, further comprising:

70. Before A) above, A third user input regarding the range of the target refractive index for the RTU flame retardant product is received via the user interface. The method according to claim 44, further comprising:

71. Before A) above, A third user input regarding the range of the target refractive index for the RTU flame retardant product is received via the user interface. The method according to claim 52, further comprising:

72. Before A) above, A third user input regarding the range of the target refractive index for the RTU flame retardant product is received via the user interface. The method according to claim 66, further comprising:

73. The above C) is, C1) A step of comparing a first refractive index measurement among the plurality of refractive index measurements generated in B) in a first time period with the range of the RTU flame retardant product relative to the target refractive index, C2) If the first refractive index measurement of the RTU flame retardant product is within the range of the target refractive index of the RTU flame retardant product, the single automated proportional mixing valve maintains at least one flow parameter for each of the LC flame retardant and the water, C3) If the first refractive index measurement of the RTU flame retardant product is not within the range of the target refractive index of the RTU flame retardant product, the steps of adjusting the at least one flow parameter for the LC flame retardant and the water, respectively, using the single automated proportional mixing valve, The method according to claim 13, further comprising:

74. The above C) is, C1) A step of comparing a first refractive index measurement among the plurality of refractive index measurements generated in B) in a first time period with the range of the RTU flame retardant product relative to the target refractive index, C2) If the first refractive index measurement of the RTU flame retardant product is within the range of the target refractive index of the RTU flame retardant product, the single automated proportional mixing valve maintains at least one flow parameter for each of the LC flame retardant and the water, C3) If the first refractive index measurement of the RTU flame retardant product is not within the range of the target refractive index of the RTU flame retardant product, the steps of adjusting the at least one flow parameter for the LC flame retardant and the water, respectively, using the single automated proportional mixing valve, The method according to claim 36, further comprising:

75. The above C) is, C1) A step of comparing a first refractive index measurement among the plurality of refractive index measurements generated in B) in a first time period with the range of the RTU flame retardant product relative to the target refractive index, C2) If the first refractive index measurement of the RTU flame retardant product is within the range of the target refractive index of the RTU flame retardant product, the single automated proportional mixing valve maintains at least one flow parameter for each of the LC flame retardant and the water, C3) If the first refractive index measurement of the RTU flame retardant product is not within the range of the target refractive index of the RTU flame retardant product, the steps of adjusting the at least one flow parameter for the LC flame retardant and the water, respectively, using the single automated proportional mixing valve, The method according to claim 52, further comprising:

76. The above C) is, C1) A step of comparing a first refractive index measurement among the plurality of refractive index measurements generated in B) in a first time period with the range of the RTU flame retardant product relative to the target refractive index, C2) If the first refractive index measurement of the RTU flame retardant product is within the range of the target refractive index of the RTU flame retardant product, the single automated proportional mixing valve maintains at least one flow parameter for each of the LC flame retardant and the water, C3) If the first refractive index measurement of the RTU flame retardant product is not within the range of the target refractive index of the RTU flame retardant product, the steps of adjusting the at least one flow parameter for the LC flame retardant and the water, respectively, using the single automated proportional mixing valve, The method according to claim 66, further comprising:

77. The above C) is, C1) A step of comparing a first refractive index measurement among the plurality of refractive index measurements generated in B) in a first time period with the range of the RTU flame retardant product relative to the target refractive index, C2) If the first refractive index measurement of the RTU flame retardant product is within the range of the target refractive index of the RTU flame retardant product, the single automated proportional mixing valve maintains at least one flow parameter for each of the LC flame retardant and the water, C3) If the first refractive index measurement of the RTU flame retardant product is not within the range of the target refractive index of the RTU flame retardant product, the steps of adjusting the at least one flow parameter for the LC flame retardant and the water, respectively, using the single automated proportional mixing valve, The method according to claim 69, further comprising:

78. The above C) is, C4) If a fourth user input relating to stopping the operation of at least one pump is received via the user interface, the steps of stopping the at least one pump in A) are performed. C5) In the following cases: A fifth user input regarding a preset amount of the RTU flame retardant product is received via the user interface, and If the amount of the RTU flame retardant product pumped through the at least one conduit is equal to, approximately equal to, or exceeds the preset amount of the RTU flame retardant product, The step in A) above is to stop at least one of the pumps, The method according to claim 69, further comprising:

79. The above C) is, C4) If a fourth user input relating to stopping the operation of at least one pump is received via the user interface, the steps of stopping the at least one pump in A) are performed. C5) In the following cases: A fifth user input regarding a preset amount of the RTU flame retardant product is received via the user interface, and If the amount of the RTU flame retardant product pumped through the at least one conduit is equal to, approximately equal to, or exceeds the preset amount of the RTU flame retardant product, The step in A) above is to stop at least one of the pumps, The method according to claim 73, further comprising:

80. C6) A step in which the steps of C1) and either C2) or C3) are repeated in a second time period using the second refractive index measurement among the plurality of refractive index measurements. The method according to claim 73, further comprising:

81. The first refractive index measurement value of the RTU flame retardant product is not within the range of the target refractive index of the RTU flame retardant product, The method according to claim 80, wherein C3) comprises the step of operating the single automated proportional mixing valve to adjust the at least one flow variable for each of the LC flame retardant and the water such that the inline refractive index of the RTU flame retardant product changes by about 0.1 with respect to the arbitrary 10440VP scale in B).

82. The aforementioned C6) is, C6a) A step of waiting for a predetermined period following C3), C6b) After waiting for the predetermined period, the step of C1) and either step C2) or C3) are repeated for a second time using the second refractive index measurement value among the plurality of refractive index measurements, The method according to claim 81, comprising:

83. The aforementioned B) is, B1) To generate the plurality of refractive index measurements for the RTU flame retardant product, the steps of automatically and repeatedly measuring the in-line refractive index of the RTU flame retardant product by an in-line refractometer located in the at least one conduit between the single automated proportional mixing valve and the flow meter associated with the aircraft, as the RTU flame retardant product is pumped through the at least one conduit, B2) To generate multiple density measurements for the RTU flame retardant product, the in-line density of the RTU flame retardant product is automatically and repeatedly measured by the flow meter associated with the aircraft as the RTU flame retardant product is pumped through the at least one conduit, Equipped with, The above C) is, In order to achieve the target refractive index of the RTU flame retardant product in the range of 8 to 30 for any 10440VP scale, the single automated proportional mixing valve automatically adjusts or maintains at least one flow variable for each of the LC flame retardant and the water, based at least to some extent on the plurality of refractive index measurements generated in B1) and the plurality of density measurements generated in B2). The method according to claim 13, comprising:

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