Method and apparatus for dynamically determining permeability of a porous solid

Abstract

Disclosed herein is a method and apparatus for dynamically adjusting a pressure ramp to maximize resolution of capillary porosity of a porous material. The method dynamically increases a pressure ramp rate applied to a wetting sample as a rate of change of mass flow rate decreases, and dynamically decreases the pressure ramp rate as the rate of change of mass flow rate increases. The method can further control sensitivity of the pressure ramp to changes in mass flow rate, and can apply a resolution parameter to control the rate of pressure change.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims the benefit of U.S. Provisional Patent Application No. 63 / 617,962, filed January 5, 2024, and claims the benefit of U.S. Provisional Patent Application No. 63 / 713,808, filed October 30, 2024.

[0002] INCORPORATION BY REFERENCE The disclosures made in U.S. Provisional Patent Application No. 63 / 617,962, filed January 5, 2024, and U.S. Provisional Patent Application No. 63 / 713,808, filed October 30, 2024, are specifically incorporated by reference herein, in their entirety, as if set forth in their entirety. TECHNICAL FIELD

[0003] The subject matter of the present invention relates generally to the field of porometry or the measurement of the porosity of a substance. In particular, the present disclosure relates to a method for determining the pore size and pore size distribution of a porous material as a function of a driving variable using a wetting fluid to pass through the pores, and embodiments of an apparatus for use in the method. BACKGROUND

[0004] In the field of porometry, the pore size and pore size distribution of a sample of a porous material can be measured under the control of pressure and mass flow. When the sample is dry, all of the pores are evacuated, so gas flows in proportion to the amount of pressure added. After wetting the sample, all of the pores are filled with the wetting fluid, so that gas does not flow through the blocked pores. However, as the pressure is increased, the pores are opened as the wetting fluid is forced through the sample. Pores with larger effective diameters are opened at lower pressures than pores with smaller effective diameters. The passage of gas flow through the largest pore is the bubble point of the sample. As the pressure continues to increase, the pores in the sample continue to be evacuated until all of the pores are evacuated. The pore distribution of the sample is calculated using the ratio between the wet and dry flow measurements.

[0005] In a conventional capillary flow porometry analysis, the sample is fully wetted with a fluid having a known surface tension, and pressure is applied to the sample by a pressure ramp or pressure step to identify the first bubble point. The process continues by increasing the pressure until all of the pores in the sample are opened, which is shown as a wet curve. The pressure can then be decreased until no flow is detected, which defines a dry curve, and can be a dry upstroke curve or a dry downstroke curve as shown. Typically, two methods for capillary flow porometry testing of a sample are conventionally used, a pressure ramp and a pressure step.

[0006] In a conventional pressure ramp, the pressure increases continuously at a constant rate. This provides a rapid and repeatable method, often recommended for quality control work and for samples with identical orifices. However, a problem arises when the sample has a complex structure with a comparable number of orifices of varying curvature. During a constant pressure ramp, orifices with the same diameter but longer or more curved paths may not be emptied at the pressure corresponding to their respective diameters. In such cases, if the pressure ramp is rapid, there is insufficient time for the airflow to displace the wetting liquid along the orifice length. Consequently, orifices with longer orifice lengths will be reported as having smaller orifice diameters than their actual size. Therefore, while this pressure ramp method is faster than the conventional pressure stepping method, it can reduce resolution, specifically in curved test samples where orifices of similar size have different and time-dependent flow paths.

[0007] In conventional pressure stepping, the pressure increases in a series of predetermined steps, including a settling period after each corresponding step. It should be understood that the settling period helps minimize errors caused by varying sample curvature and orifice lengths with the same diameter. In this method, measurements are typically obtained after maintaining a constant pressure for a predetermined time and allowing the gas flow through the sample to stabilize, allowing sufficient time for the gas flow to displace the wetting liquid in longer, more curved orifices of the same diameter. Pressure stepping combined with controlled flow further allows for the measurement of the true first bubble point, compared to pressure ramp methods that only allow calculation of the first bubble point at the measured flow rate. Conventional pressure stepping, settling, and measurement methods require undesirable trade-offs between measurement resolution and overall test time. Smaller pressure steps within a pressure range typically yield higher resolution but require a correspondingly longer time to complete. Conversely, larger pressure steps within a pressure range typically yield lower resolution but require a shorter time to complete.

[0008] Conventional methods require a trade-off between resolution and overall testing time to help achieve measurement objectives. Therefore, there is a need in the art for a method and apparatus that improves the speed of obtaining high-resolution determinations of capillary porosity in porous materials. Summary of the Invention

[0009] Various aspects and advantages of the invention will be set forth in part in the description which follows, or may be apparent from the description, or may be learned by practice of the invention.

[0010] Embodiments of the inventive concepts disclosed herein relate to methods and apparatus for determining capillary flow porosity of porous samples, wherein the methods and apparatus monitor and control applied pressure based on user-programmable parameters and maximum and minimum limits, according to variations in the pore size and pore size distribution of the porous material sample under test. This is determined in part by the pressure applied across the porous material sample under test and the gas mass flow rate through the porous material sample.

[0011] The method described herein reduces the time required to determine the pore size and pore size distribution of porous material samples while improving measurement resolution. In an embodiment, the method uses a pressure ramp to achieve rapid measurement and dynamically slows the increase of the pressure ramp to approach a constant pressure, which is a function of the gas flow rate. The achieved slower pressure increase and near-constant pressure enable the determination of the sample's porosity at high resolution. This method is designed to minimize test time while improving the resolution of capillary flow porosity measurements.

[0012] The method described herein dynamically adjusts the pressure ramp to maximize resolution during orifice opening. Specifically, the method dynamically increases the pressure ramp rate as the mass flow rate changes, and dynamically decreases the pressure ramp rate as the mass flow rate changes. Optionally, and to further improve the resolution of porosity measurements, user parameters can be applied to control the sensitivity of the pressure ramp to changes in mass flow rate, and resolution parameters can be used to control the rate of pressure change.

[0013] In one instance, the applied test pressure ramp is modified exponentially and can be controlled between defined minimum and maximum pressure ramp rates. In this respect, the maximum pressure ramp can be applied when the mass flow rate is constant, and the maximum pressure ramp can approach zero as the mass flow rate increases.

[0014] In this method, the applied pressure rate can be dynamically adjusted based on a set of user-adjustable parameters, which include at least one of the following three: the maximum pressure ramp rate; a resolution parameter for controlling the deceleration of the ramp rate; and a sensitivity parameter for controlling how sensitive the pressure change rate is to changes in the gas flow rate.

[0015] The following discussion details these exemplary aspects and embodiments, as well as other aspects, embodiments, and advantages. Furthermore, it should be understood that the foregoing information and the following detailed description are merely illustrative examples of aspects and embodiments, and are intended to provide an overview or framework for understanding the nature and characteristics of the claimed aspects and embodiments. Therefore, these and other objects, advantages, and features of the invention disclosed herein will become apparent from the following description and accompanying drawings. Moreover, it should be understood that the features of the various embodiments described herein are not mutually exclusive and can exist in various combinations and arrangements. Attached Figure Description

[0016] The accompanying drawings, included to provide a further understanding of embodiments of the present disclosure, are incorporated in and form part of this specification. They illustrate embodiments of the present disclosure and, together with the detailed description, serve to explain the principles of the embodiments discussed herein. No attempt is made to show the structural details of the present disclosure beyond the level of detail that may be required for a basic understanding of the exemplary embodiments discussed herein, and various ways in which the exemplary embodiments may be practiced. By convention, various features in the drawings discussed below are not necessarily drawn to scale. The dimensions of various features and elements in the drawings may be enlarged or reduced to more clearly illustrate embodiments of the present disclosure.

[0017] FIG. 1 This is a schematic diagram illustrating an example of sample wetting and the wetting angle of the Washburn equation.

[0018] FIG. 2 A schematic cross-section of a sample with wetted and open pores is shown.

[0019] FIG. 3 An exemplary curved flow path length through a porous material sample is shown.

[0020] FIG. 4 This is a schematic diagram of one implementation of the device.

[0021] FIG. 5 This is a schematic diagram of one implementation of the device.

[0022] FIG. 6 This is a schematic diagram illustrating one embodiment of a device for a control subsystem.

[0023] FIG. 7 A schematic flowchart is shown for dynamically determining the pressure ramp rate.

[0024] FIG. 8 An example of pressure-to-flow rate analysis using an implementation of the method of this disclosure is shown.

[0025] FIG. 9 An example of aperture determination is shown.

[0026] FIGS. 10A-10D This is a graph of the gas flow through the sample assuming quasi-steady-state behavior, a linear ramp rate of 0.05 psi / s, a wetting agent surface tension of 16.3 dyn / cm, a contact angle of 0 degrees, a sampling rate of 10 Hz, a final pressure of 500 psig, and an initial pressure of 0.019 psig. As shown, the conventional linear pressure ramp (blue line) is too "fast" for large pores in the sample, but conversely too "slow" for small pores in the same sample. The dynamic and exponential pressure stepping method (red line) provides a faster overall determination of porosity and allows for substantially the same uncertainty (i.e., measurement error divided by pore size) across every pore measurement throughout the pore size range. As shown, the dynamic and exponential pressure stepping method employs smaller or larger pressure steps where appropriate (large pressure steps can be used when measuring small pores, and small pressure steps can be used when measuring large pores).

[0027] FIG. 11 The time-series data results of an exemplary 1.0 μm nominal pore size thin filter sample using a 0.2 psi / s linear ramp mode are presented graphically, showing the applied T1 pressure (psig), flow rate (slpm), and flow / pressure, and illustrating the resulting wet boost, dry depressurization, and dry boost cycles.

[0028] FIG. 12 It is displayed graphically. FIG. 11 The time series data were converted into a graph of flow rate versus pressure, showing the applied T1 pressure (psig), flow rate (slpm), and flow rate / pressure.

[0029] FIG. 13 It is displayed graphically. FIG. 11 The time series data were converted into a flow / pressure versus orifice pressure graph. The conversion from pressure to orifice size in this graph assumes a contact angle of zero and a tortuosity of 1.0 (for a given surface tension of the wetting fluid, this makes orifice size = 9.1 / pressure, where pressure is in psig).

[0030] FIG. 14 It is displayed graphically. FIG. 13 The flow / pressure versus orifice pressure curve data is converted into a slope versus orifice diameter curve, where the slope is... FIG. 13 The slope of the corresponding flow / pressure data points is plotted, and the pore size of the sample collected at approximately 0.76 μm is shown graphically.

[0031] FIG. 15The time-series data results for an exemplary filter sample with two discrete pore sizes are presented graphically. The graphs were derived using a linear ramp mode at 0.2 psi / s, showing the applied T1 pressure (psig), flow rate (slpm), and flow rate / pressure.

[0032] FIG. 16 It is displayed graphically. FIG. 15 The time series data was converted into a slope versus aperture curve, where the slope is derived from... FIG. 15 The slopes of the corresponding determined flow / pressure data points were obtained, and the pore sizes of the samples collected at approximately 1.375 μm and 2.645 μm pore sizes were graphically shown.

[0033] FIG. 17 The flow rate versus pressure data of an exemplary 0.05 µm nominal pore size thin filter sample using a 0.2 psi / s linear ramp mode are graphically presented, showing the applied T1 pressure (psig), flow rate (slpm), and flow rate / pressure.

[0034] FIG. 18 The results of flow rate versus pressure for an exemplary 12.0 µm nominal pore size thin filter sample using a 0.2 psi / s linear ramp mode are presented graphically, showing the applied T1 pressure (psig), flow rate (slpm), and flow rate / pressure.

[0035] FIG. 19 The results of flow rate versus pressure for an exemplary 1.0 μm nominal pore size thin filter sample using a 0.2 psi / s linear ramp mode are presented graphically, showing the applied T1 pressure (psig), flow rate (slpm), and flow rate / pressure.

[0036] FIG. 20A and 20B An embodiment of a sample adapter plate with plate members is shown, the plate members being configured with a central hole whose size and shape are operatively set to accommodate a porous test sample, such as the woven test mesh filter sample exemplarily shown.

[0037] FIG. 21 An embodiment of a sample adapter plate is shown, illustrating a plate component having a central hole and an O-ring. The central hole is configured to operatively receive a woven test mesh filter sample, which is positioned in a stacked relationship to a lower fine mesh sieve. The O-ring is used to seal the hole for testing. An optional coarse sieve is also shown.

[0038] FIG. 22An embodiment of a test stack profile for positioning holes in an adapter plate is shown. In this embodiment, the test stack includes a woven test mesh filter sample positioned between an upper and a lower fine mesh screen. A biasing device, such as an O-ring, is applied to ensure that the formed test stack is in a compressed state, thereby compressing the fibers forming the woven test mesh filter sample together to form a test sample with a more uniform porosity.

[0039] FIG. 23A and 23B A micrograph of an exemplary woven test filter sample is shown. FIG. 20A A micrograph of a 70 μm woven mesh filter (measured at 65 μm) is shown. FIG. 20B A micrograph of a 53 μm woven mesh filter (measured at 50 μm) is shown.

[0040] FIG. 24 and 25 The following is illustrated graphically: FIG. 22 The test results are shown for an exemplary test stack profile. In this example, a 53 μm woven test mesh filter sample is positioned between identical upper and lower fine mesh screens with 250 μm pores. As shown, test “A” and multiple repeated runs (“B”, “C”, “D”, “E”) are run multiple times with the wetted sample without rewetting. As shown in “A”, the sample is placed... FIG. 18 The exemplary test stack profile shown yields a significantly smaller FBP / BP with excellent accuracy (0.1-0.2% RSD).

[0041] FIG. 26 and 27 The following is illustrated graphically: FIG. 22 The test results for the exemplary test stack profile are shown. In this example, a 70 μm woven polyester test filter sample is positioned between the same upper and lower fine mesh screens formed with (250 μm pores). As shown, test “A” and multiple repeated runs (“B”, “C”, “D”, “E”) are run multiple times without rewetting the sample, with the sample wetted. As shown, the test using a 70 μm polyester mesh and sample plates (250 μm pores) positioned above and below the test mesh filter shows a close grouping of FBP and BP (0.1–0.2% RSD). Additionally, in the exemplary sample test, the bubble point pore size (average: 95.03 μm) is closer to the pore size calculated based on the thread diameter and pitch (103.02 μm) than the nominal manufacturer's pore size (70 μm).

[0042] FIG. 28An embodiment of an adjustable sample plate assembly is shown, which is configured to accommodate a test filter sample having a relatively thick height. A hinged or sliding seal assembly is shown, which is configured to apply a bias to ensure proper operative positioning of the O-ring against the outer edge of the test filter sample within the test hole of the sample plate assembly.

[0043] FIG. 29 An embodiment of the sample chamber is shown, which includes a cover configured to be threadedly connected to a first flow line in fluid communication with the inlet side of the sample chamber, and a cover configured to be threadedly connected to a complementary thread throat in fluid communication with the internal volume of the sample chamber, into which a wetted orifice sample can be installed for testing.

[0044] FIGS. 30A-30D One embodiment of the cover is shown, the cover defining at least one cover recess extending from the distal edge of the threaded portion of the cover to approach the lower surface of the top member. As further shown, the at least one cover recess is spaced apart from the end of the thread near the lower surface of the top member.

[0045] FIGS. 31A-31D An embodiment of a throat having a circumferential wall is shown, the circumferential wall extending from a top surface of a bottom member of the throat near the circumferential edge of the bottom member, and extending distally from the top surface substantially transverse to the plane of the bottom member. As shown, the throat may define at least one throat groove extending from the proximal edge of the threaded circumferential wall portion of the throat to approach the top surface of the bottom member. Detailed Implementation

[0046] The invention can be more readily understood by referring to the following detailed description, examples, drawings, and claims, as well as the description preceding and following them. However, before disclosing and describing the apparatuses, systems, and / or methods of the invention, it should be understood that, unless otherwise stated, the invention is not limited to the specific apparatuses, systems, and / or methods disclosed, and therefore, variations are naturally possible. It should also be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.

[0047] The following description of the invention is provided as a teaching facilitating the invention in its best, currently known, implementation. Therefore, those skilled in the art will recognize and understand that many changes can be made to various aspects of the invention described herein while still obtaining the beneficial results of the invention. It will also be apparent that some of the desired benefits of the invention can be obtained by selecting some features of the invention without utilizing others. Therefore, those skilled in the art will recognize that many modifications and adaptations to the invention are possible, and in some cases even desirable and part of the invention. Thus, the following description is provided as an illustration of the principles of the invention and not as a limitation thereof.

[0048] As used throughout this document, unless the context clearly indicates otherwise, the singular forms “a / an” and “the” include plural indicators. Thus, for example, unless the context clearly indicates otherwise, a reference to “hole” may include two or more such holes.

[0049] In this document, a range may be expressed as from “about” a specific value and / or to “about” another specific value. When expressing such a range, the other side includes from said one specific value and / or to said other specific value. Similarly, when a value is expressed as an approximation using the antecedent “about,” it should be understood that the specific value forms the other side. It should also be understood that the endpoints of each range are significant both relative to and independent of the other endpoint. It should be understood that approximation terms such as “about” or “approximately,” as used herein, refer to a range within 10% error.

[0050] As used herein, the terms “optional” or “optionally” mean that the event or situation described below may or may not occur, and the description includes both cases where the event or situation occurs and cases where the event or situation does not occur.

[0051] As used herein, the term "first bubble point" refers to the pressure at which the displacement fluid begins to flow through the pores of a porous material sample.

[0052] As used herein, the term “wet profile” is a representation of the measured airflow relative to the applied pressure on a wet sample.

[0053] As used herein, the term “dry profile” is a representation of the measured airflow over a dried sample relative to the applied pressure.

[0054] As used herein, the term “curvature” refers to a deviation from a straight path described by the geometry of the hole, such as bends, multiple narrowings of the hole diameter along its length, and branching of a through hole.

[0055] As used herein, the term “aperture” refers to the operating width between the two opposing walls of an aperture.

[0056] As used herein, the term “pore size distribution” refers to the statistical distribution of pore sizes in a sample, where the radius of the equivalent maximum sphere that can be fitted into the through-hole at the narrowest point defines the size of the pore.

[0057] As used herein, the term "pressure difference" refers to the pressure difference between the pressure applied to either side of a porous sample being tested and the ambient pressure.

[0058] As used herein, the word “or” means any one member of a particular list, and also includes any combination of members of said list. Furthermore, it should be noted that, unless explicitly stated otherwise or otherwise understood in the context in which it is used, conditional language such as “can / could / might or can” is generally intended to convey that certain aspects include certain features, elements, and / or steps while others do not. Therefore, such conditional language is not generally intended to imply that features, elements, and / or steps are necessary in any given situation for one or more particular aspects, or that one or more particular aspects must include logic for determining whether such features, elements, and / or steps are included in or will be performed in any particular implementation, with or without user input or prompting.

[0059] The wording and terminology used herein are for illustrative purposes and should not be considered restrictive. As used herein, the term "a plurality of" means two or more items or components. Whether in the written description or in the claims, the terms "comprising or including," "carrying," "having," "containing," and "involving" are open-ended terms, meaning "including / comprises but not limited to." Therefore, using these terms implies coverage of the items listed thereafter, their equivalents, and additional items. With respect to any claim, only the transitional phrases "consisting of..." and "consisting substantially of..." are closed or semi-closed transitional phrases, respectively. The use of ordinal terms such as "first," "second," and "third" to modify a claim element itself does not imply any priority, order, or sequence of actions of a method relative to another claim element, but is merely a label to distinguish one claim element with a specific name from another element with the same name (but using ordinal terms) to differentiate claim elements.

[0060] Components that can be used to perform the disclosed methods and apparatus are disclosed herein. These and other components are disclosed herein, and it should be understood that while specific references to every individual and collective combination and arrangement of these components are not explicitly disclosed when disclosing combinations, subsets, interactions, groups, etc., of these components, each combination and arrangement is specifically considered and described herein for all methods and systems. This applies to all aspects of this application, including but not limited to the steps in the disclosed methods. Therefore, if various additional steps exist that can be performed, it should be understood that each of these additional steps can be performed using any particular implementation or combination of implementations of the disclosed methods.

[0061] The methods and apparatus of the present invention can be more readily understood by referring to the following detailed description of preferred embodiments and the examples included therein, as well as the accompanying drawings and their preceding and following descriptions.

[0062] Embodiments of the inventive concept disclosed herein relate to methods and apparatus for determining capillary flow porosity in porous samples, wherein the methods and apparatus monitor and control the applied pressure based on changes in the pore size and pore size distribution of the porous material sample under test, using user-programmable parameters and maximum and minimum limits. This is determined in part by the pressure applied across the porous material sample under test and the gas mass flow rate through the porous material sample. Exemplary embodiments of the methods and apparatus are described below with reference to the accompanying drawings.

[0063] refer to FIG. 1 This illustrates an example of a wetting fluid applied to a sample. The wetting fluid can typically comprise various types of fluids with known surface tensions and is uniformly distributed across the sample to achieve a zero-degree contact angle, such as... FIG. 1 and 3 As indicated. Those skilled in the art will understand that "contact angle" does not simply mean "uniformly distributed on a surface," but rather indicates the wettability of a liquid on a solid sample.

[0064] Subsequently, in such FIG. 3 In the illustrated embodiment, when gas is applied under pressure to a fully wetted sample, the wetting fluid is forced through the sample. For example... FIG. 3 As further indicated, the orifices will be emptied based on orifice size, with the largest orifice emptied first. In an embodiment, the gas pressure drop indicating that the indicative gas has passed through the largest orifice is the bubble point of the sample (when mass gas flow rate is controlled). The bubble point is typically determined by starting with sample material saturated with a wetting agent and subsequently increasing the gas pressure on the upstream side until capillary forces are overcome, and can be determined by measuring the decrease in gas flow rate or gas pressure (when mass gas flow rate is controlled).

[0065] At the bubble point, the largest pore empties first, which defines the maximum pore size. Based on the Laplace equation for known capillary pressures, once the bubble point is determined, the diameter of the largest pore throat can be calculated. It can be understood that at increasingly higher pressures, smaller and smaller pores empty, and the eventual increase in gas flow rate is measured.

[0066] Based on further applied pressure, the pore size range of the sample can be calculated using the idealized Washburn equation, which assumes a tortuosity of 1 and a cylindrical pore shape of equal length, and is defined as follows: ΔP = 4 * γ * cos θ / D in: ΔP - is the applied pressure (atmospheric pressure at the bottom of the sample); D - is the diameter of the most constricted part of the hole; γ - is the surface tension at the gas-liquid interface; and θ - is the wetting angle between the membrane and the solid matrix.

[0067] Although FIG. 2 This demonstrates a more linear flow of pressurized gas through a sample; however, in most cases, and specifically for thicker samples, the gas flow path through the sample will not be straight but will become more tortuous. For example, as... FIG. 3 As shown, when gas flows through a porous material, it typically encounters branches and paths of varying lengths and throat sizes. Therefore, even with equal pore diameters, the time required for gas to pass through the material can differ. As will be understood, bends, multiple narrowings of the pore diameter along its length, and branching of the through-hole all contribute to the curvature of the sample, but the measured pore diameter is the size of the narrowest throat constraint along the curved path. Curvature is the deviation of the straight path through the sample described by the pore geometry. However, the Washburn equation assumes that every path is a perfect cylindrical shape. Therefore, a shape factor derived empirically can be applied to correct for curvature and shape; the Washburn equation is enhanced as follows when θ is 0 degrees and cos θ = 1: D = 4 * S * γ / ΔP in: S - is a shape factor derived empirically.

[0068] refer to FIG. 4An exemplary embodiment of the apparatus according to the invention is configured to measure the permeability of a solid sample. The apparatus includes a sample chamber having an internal volume including a sample holder for holding a porous solid sample for the duration of an experimental procedure. The internal volume of the sample chamber defines an inlet side and an outlet side, separated by the sample holder. The apparatus includes a first flow line in fluid communication with the internal volume of the sample chamber on the inlet side. The internal volume of the sample chamber on the outlet side is in fluid communication with the atmosphere. The first flow line has a first valve disposed therein.

[0069] As exemplarily shown and referenced FIG. 5 The first flow line is in fluid communication with multiple gas sources, such as, but not limited to, exemplified 100 psi and 500 psi gas sources, and multiple pressure measuring devices or sensors in the form of pressure transducers, which may have different pressure sensitivities. The application of gas from the respective multiple gas sources is controlled by using first and second pressure regulators (actuators). The first pressure actuator is downstream of and in fluid communication with the multiple gas sources, and in fluid communication with a downstream second pressure regulator. The first pressure regulator is also in fluid communication with multiple flow meters and flow controllers. As exemplarily shown, the multiple flow meters, flow controllers, and second pressure regulator are in fluid communication with a common manifold located upstream of and in fluid communication with a first valve of the first flow line.

[0070] refer to FIG. 5 In an embodiment, the device is designed to regulate the inlet pressure of the chamber and allow dynamic control of the pressurized gas to be applied to the target sample within the chamber, as well as dynamic control of the mass flow rate of the gas supplied to the target sample as a pressurized gas stream.

[0071] On the one hand and refer to FIG. 6The device can be configured to house a control subsystem, which can be configured to include electronic controls, computer systems, programming, etc., required for device operation. Therefore, in this respect, it is conceivable that the device's control subsystem may include a processing system having control modules and instrument controllers, the processing system including at least one processor and at least one memory, the processing system being coupled to volatile or non-volatile memory containing a database for storing information related to the operation of the device. The memory is configured to contain instructions that, when executed by the processor, are operable to perform basic, recommended, and / or optional functions in the various embodiments of the device described herein. In this respect, the control subsystem has at least one memory configured to store program instructions, such that, in operation, at least one memory of the control subsystem is configured to store program instructions that, when executed, cause the device to perform the required operations.

[0072] To regulate the operation of the equipment, the control subsystem may include input devices (such as one of the pressure transducers, which may be a high-pressure transducer (500 psi) or a low-pressure transducer (5 psi or 25 psi), and a mass flow meter) and output devices (such as pressure regulators, mass flow controllers, and control valves) operatively coupled to the processor. In an embodiment, the control subsystem is configured to allow real-time control and operative communication and control of the first and second pressure regulators, system control valves, and mass flow meter and controller.

[0073] In an exemplary aspect, the control subsystem is configured to receive data from a mass flow meter regarding the corresponding mass flow rate of the supplied pressurized flow and from a pressure measuring device regarding the sensed gas pressure. The control subsystem includes memory in communication with a processor and may also include other features such as limiters, regulators, filters, format converters, etc., which are not shown for clarity. One or more operator input devices may also be coupled to the instrument controller to provide corresponding operator input to adjust / guide one or more aspects of equipment operation. Exemplary input devices may include, but are not limited to, keyboards, mice, pens, voice input devices, gesture input devices, and / or touch input devices or any other suitable input devices. The control subsystem may further include one or more output devices coupled to the instrument controller, such as displays, printers, and / or speakers, or any other suitable output devices. However, in other embodiments, the computer-readable communication medium may include computer-readable instructions, program modules, or other data transmitted within data signals such as carrier waves or other transmissions. Optionally, the control subsystem may also include audible alarms, warning lights, etc. (not shown), which may also be coupled to the controller, each responding to various output signals from the controller.

[0074] More specifically, the control subsystem is configured to implement certain systems and methods for operating a device according to certain embodiments of this disclosure. The processor is configured to perform certain operational aspects associated with implementing some of the systems and methods described herein. The processor can be implemented and operated using suitable hardware, software, firmware, or a combination thereof. Software or firmware implementations may include computer-executable or machine-executable instructions written in any suitable programming language for performing the various functions described herein. In some instances, instructions associated with a function block language may be stored in memory and executed by the processor.

[0075] As will be understood, memory can be used to store program instructions, such as instructions for performing the methods shown herein or other suitable variations. Memory can include, but is not limited to, operating systems and one or more application programs or services for implementing the features and implementations disclosed herein. Instructions can be loaded and executed by a processor and stored in data generated during the execution of these programs. Depending on the configuration and type of the control subsystem, memory can be volatile (e.g., random access memory (RAM)) and / or non-volatile (e.g., read-only memory (ROM), flash memory, etc.). In some embodiments, the memory device can include additional removable and / or non-removable storage devices, including but not limited to magnetic storage devices, optical disk and / or magnetic tape storage devices. Disk drives and their associated computer-readable media can provide non-volatile storage of computer-readable instructions, data structures, program modules, and other data for the device. In some embodiments, memory includes various different types of memory, such as static random access memory (SRAM), dynamic random access memory (DRAM), or ROM.

[0076] Memory, removable storage devices, and non-removable storage devices are all examples of computer-readable storage media. For example, computer-readable storage media can include volatile and non-volatile, removable and non-removable media implemented using any method or technology for storing information such as computer-readable instructions, data structures, program modules, or other data. Other types of computer storage media that may exist include, but are not limited to, programmable random access memory (PRAM), SRAM, DRAM, RAM, ROM, electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, optical disc read-only memory (CD-ROM), digital versatile optical disc (DVD) or other optical storage devices, magnetic tape cassettes, magnetic tape, disk storage devices or other magnetic storage devices, or any other medium that can be used to store desired information and is accessible by a device. Any combination of the above should also be included within the scope of computer-readable media.

[0077] The control subsystem may also include one or more communication connections that allow the control device (not shown) to communicate with devices or equipment capable of communicating with the control subsystem. Connections may also be established via various data communication channels or ports (such as USB or COM ports) to accommodate cables connecting the control subsystem to various other devices on the network. In one embodiment, the control subsystem may include an Ethernet driver enabling the control subsystem to communicate with other devices on the network. According to various embodiments, communication connections may be established via wired and / or wireless connections on the network.

[0078] The operation of the apparatus will now be described. The sample is initially sealed in the chamber, and pressurized gas is controllably delivered to the fully wetted surface of the sample. The gas pressure and mass flow rate are selectively controlled throughout the testing process. As will be understood, the described dynamic method reduces the time required to determine the pore size and pore size distribution of porous material samples while improving the resolution of the measurement.

[0079] In one embodiment, the method may initially supply a linear pressure ramp scheme until a bubble point is determined. Optionally, the method may initially supply a pressure step and / or pressure ramp scheme until a bubble point is determined. In an embodiment of the invention, a constant flow rate is initially delivered to the test chamber, and the rate of pressure rise is measured to determine the first bubble point. In this respect, a very low constant flow rate (10-100 sccm) can be used to allow easy determination of the decrease in the rate of pressure rise when the first orifice opens (e.g., at the first bubble point). In one embodiment, the method may determine the first bubble point before initiating a full porosity measurement scan.

[0080] In this implementation, the method uses a pressure ramp to achieve rapid measurement and combines it with a technique that exponentially slows down the rate of the pressure ramp to approach a constant pressure, which is a function of the gas flow rate change. Therefore, in this implementation, the pressure is ramped up using a linear pressure ramp method or a pressure stepping method until a bubble point is determined. At this bubble point, the method deviates from the linear pressure ramp method by dynamically and exponentially changing the linear slope of the pressure change to slow down the increase of the pressure ramp, thereby approaching a constant pressure, which is a function of the gas flow rate change. At this constant pressure, data on the porosity of the sample, as a function of the point of gas flow rate change, can be obtained, enabling the determination of the sample's porosity at high resolution. As will be understood, this method is designed to minimize test time while improving the resolution of capillary flow porosity measurements.

[0081] In methods of pressurizing a sample chamber system, it is common for any change in pressure to generate a charging flow that is directed to pressurize the sample chamber volume. In an alternative embodiment, it is conceivable that this charging flow can be determined and corrected for with respect to the pressure ramp of the described test method.

[0082] In an alternative implementation, pressure can be envisioned to increase gradually using a linear pressure ramp method or a pressure stepping method until a bubble point is determined. At the bubble point, the method deviates from the linear pressure ramp method by exponentially changing the linear slope of the pressure change to slow the increase of the pressure ramp, thereby approaching a constant pressure, which is a function of the gas flow rate. In another alternative implementation, pressure can be envisioned to increase gradually using a nonlinear function ramp method or an exponential pressure ramp method until a bubble point is determined. At the bubble point, the method deviates from the initial ramp method by exponentially changing the linear slope of the pressure change to slow the increase of the pressure ramp, thereby approaching a constant pressure, which is a function of the gas flow rate.

[0083] In an optional implementation, when a linear pressure ramp method is selected and the initial pressure is below the target pressure, the pseudo-ramp mode method can be applied, where the target pressure can be approximately 5 psig (35 kPag). In this respect, the pseudo-ramp mode method operates like a pressure stepping method, which allows for more accurate measurement of pressure and flow when the pressure is below the target pressure. Furthermore, the pseudo-ramp mode method can be configured to revert to a normal ramp mode method when the applied pressure exceeds the target pressure.

[0084] The method described herein dynamically adjusts the pressure ramp to maximize resolution during orifice opening. Specifically, the method dynamically increases the pressure ramp rate as the mass flow rate changes, and dynamically decreases the pressure ramp rate as the mass flow rate changes. FIG. 6 and FIG. 7 As shown, optionally, and in order to further improve the resolution of porosity measurements, user parameters can be applied to control the sensitivity of the pressure ramp to changes in mass flow rate, and resolution parameters can be used to control the rate of pressure change.

[0085] In another optional aspect, the applied pressure rate can be dynamically adjusted based on a set of user-adjustable parameters, which includes at least one of the following three: a maximum pressure ramp rate; a resolution parameter for controlling the deceleration of the ramp rate; and a sensitivity parameter for controlling how sensitive the pressure change rate is to changes in the gas flow rate.

[0086] refer to FIG. 8 and 9In one embodiment, an analytical method is provided for determining the pore size and pore size distribution of a porous material using a viscous wetting fluid passing through a pore. In one embodiment, the device can be selected to operate in either a high-productivity or high-resolution mode. In the high-productivity or high-resolution mode embodiment, the rate of pressure change of the gas supplied to the sample chamber can be dynamically controlled according to a function containing an exponential term. In this embodiment, and as detailed below, the exponential term may include the percentage of mass flow rate through the sample material per unit time. For example, in high-productivity mode, the exponential term / function can be selected such that the pressure ramps up at a rapid rate while the percentage of mass flow rate change through the sample material per unit time is small, wherein the rate of pressure change increases toward the maximum permissible rate of pressure change until the bubble point is reached, and then the rate of pressure change can be dynamically adjusted (e.g., reduced) according to an exponential factor based on the percentage of mass flow rate change per unit time. As will be understood, the rate of pressure change of the flow rate can approach zero as the flow rate through the sample material increases. In high-resolution mode, the function / exponential factor can be selected such that the rate of pressure change ramps up at a slower rate until the bubble point, and can then be dynamically adjusted to remain nearly zero throughout the pore opening of the sample.

[0087] refer to FIG. 8 The relationship between flow rate and pressure over time is graphically illustrated. As shown, the method of the present invention preferably significantly reduces the rate of pressure increase when the bubble point is reached. As will be understood, once the test mode reaches the average orifice diameter, the rate of change of flow rate increases rapidly. Due to this rapid rate of change of flow rate, it is desirable to obtain additional resolution of the flow rate change around the approximate average orifice diameter of the sample. Therefore, one step in the method of the present invention attempts to decrease the pressure ramp rate in the desired improved resolution region at an exponential rate as a result of the sensed flow rate increase—in contrast to the conventional linear ramp rate method. Another step in the method attempts to increase the pressure ramp rate exponentially as the sensed flow rate decreases. This cycle of exponentially decreasing the pressure ramp rate as the sensed flow rate increases and conversely, exponentially increasing the pressure ramp rate as the sensed flow rate decreases can continue to discover high-resolution data for testing samples including orifices of different diameters. FIG. 8 As shown, because the test sample is a one-micron standard filter with uniform pores of approximately one micron, only a single cycle demonstrates that the pressure ramp rate decreases / increases exponentially as the sensed fluid flow rate increases / decreases accordingly. Therefore, for samples with different pore sizes, and as... FIG. 16 As shown, such a graphical representation can be expected to include multiple such loops, each loop representing a hole of a specific size. In an exemplary aspect, FIG. 15Two pressure zones were also shown, where dynamic adjustment of the pressure ramp rate allowed for improved resolution with respect to the two illustrated apertures.

[0088] like FIG. 9 As shown, the application of a cycle in which the pressure ramp rate decreases exponentially as the sensed flow rate increases and conversely increases exponentially as the sensed flow rate decreases allows for the detection of high-resolution data for the test sample, which can graphically represent the details of the pore size in the test sample. Here, the flow rate divided by the change in pressure is plotted against the pore size, and the change in pore size is shown in detail.

[0089] In one instance, the applied test pressure ramp can be modified exponentially and controlled between defined minimum and maximum pressure ramp rates. In this respect, the maximum pressure ramp can be applied when the mass flow rate is constant, and the maximum pressure ramp can approach zero as the mass flow rate increases.

[0090] In this implementation, an exemplary exponential high-resolution ramp function for the method is described below. The high-resolution pressure ramp rate can be calculated as follows: in: K is a constant; Resolution is a parameter that affects the resolution. Sensitivity is a parameter that affects sensitivity; and = Rate of change of mass flow rate.

[0091] In this example, the numerator is the linear rate, and the denominator is an expression for slowing down the linear ramp rate as a function of flow rate variation. In this respect, the function can be executed at a periodic rate, and the resulting value represents the instantaneous pressure control setting. FIG. 9 The data shown in A-9B, 10A-10B and 11-19 were derived using the linear ramp rate described above.

[0092] Optionally, the high-resolution pressure ramp rate can be replaced by the maximum linear ramp rate (the numerator in the previous function) using the exponential ramp rate. In this exemplary aspect, the high-resolution pressure ramp rate can be calculated as follows: in: P 低 yes; u r It is an aperture uncertainty and is a constant; f It measures the sampling frequency and is a constant; K is a constant; Resolution is a parameter that affects the resolution. Sensitivity is a parameter that affects sensitivity; and = Rate of change of mass flow rate.

[0093] refer to FIGS. 10A to 10D It is worth noting that a conventional linear pressure ramp over time may be too "fast" for large pores in a sample, and conversely too "slow" for small pores in the same sample. As shown, the dynamic and exponential pressure control of this disclosure provides a faster overall determination of porosity and allows for substantially the same uncertainty (i.e., measurement error divided by pore diameter) in each pore measurement across the entire pore size range. The method of this invention achieves this by employing smaller or larger pressure steps where appropriate; for example, a large pressure step can be used when measuring small pores, and a small pressure step can be used when measuring large pores.

[0094] FIGS. 11-14 The time-series data of an exemplary 1.0 μm thin filter sample are graphically represented as a slope versus pore size plot using a 0.2 psi / s linear ramp mode. FIG. 11 The applied T1 pressure (psig), flow rate (slpm), and flow / pressure ratio are shown, and the resulting wet boost, dry depressurization, and dry boost cycles are further illustrated. FIG. 11 The data was converted into a graph of flow rate versus pressure, showing... FIG. 12 The applied pressure (psig), flow rate (slpm), and flow / pressure ratio are specified in the data. Furthermore, [the data will be used to determine the specific parameters]. FIG. 12 Data conversion FIG. 13 The graph shown is a flow rate / pressure versus orifice pressure. Finally, FIG. 13 The slope of the corresponding flow / pressure data points relative to FIG. 14 Plotting the aperture data points in the data, the... FIG. 14 The pore size of the sample collected at approximately 0.76 μm is shown graphically.

[0095] Similarly, FIGS. 15-16 The time-series data of an exemplary filter sample with two discrete pore sizes are graphically illustrated using a 0.2 psi / s linear ramp mode to convert the data into a slope versus pore size plot, showing the applied T1 pressure (psig), flow rate (slpm), and flow rate / pressure. Following the series of transformations described above, FIG. 16 It shows FIG. 15 The time series data was converted into a slope versus aperture curve, where the slope is derived from... FIG. 15The slopes of the corresponding determined flow / pressure data points were obtained, and the pore sizes of the samples collected at approximately 1.375 μm and 2.645 μm pore sizes were graphically shown.

[0096] In an alternative implementation, it is conceivable that the test method can be shortened without affecting the accuracy of the determined nominal pore size of the test filter sample. In this regard, it is conceivable that upon identifying the inflection point indicated in the flow rate versus pressure graph data, a factor N can be subsequently applied, which will truncate the ramp-up test program before the nominal time required to fully run the complete basic test program. In this regard, it is conceivable, for example and not limited to, that the factor N can be about 2, about 3, or at least 3, and that the factor N can be selectively chosen by the operator to ensure the accuracy of the truncated test program.

[0097] It is worth noting, and now for reference FIG. 17 When the inflection point was identified at approximately 150 psig, the minimum data was subsequently obtained over the remaining test time, where flow rate and pressure increased according to the standard test protocol. Therefore, in this example, it is conceivable to apply a factor of 2 and stop the test at approximately 300 psig (where the flow rate is approximately 24 slpm).

[0098] Similarly, FIG. 18 and 19 The flow rate versus pressure data for thin filter samples with different pore sizes are presented graphically. FIG. 18 In the example, a 12.0 μm nominal pore size thin filter sample using a 0.2 psi / s linear ramp mode shows the applied T1 pressure (psig), flow rate (slpm), and flow rate / pressure. Similarly, FIG. 19 The flow rate versus pressure data for an exemplary 1.0 µm nominal pore size thin filter sample using a 0.2 psi / s linear ramp mode are graphically presented, showing the applied T1 pressure (psig), flow rate (slpm), and flow rate / pressure. As shown in the figure, a test filter sample with a relatively large nominal pore size is identified (see [reference]). FIG. 18 ) and test filter samples with relatively small nominal pore sizes (see FIG. 19 The inflection point is relatively easy to reach.

[0099] FIG. 20A and 20BAn embodiment of a sample adapter plate with a plate member configured with a central hole, the size and shape of which are operatively set to accommodate a porous test sample, such as the woven test mesh filter sample exemplarily shown. It should be understood that such a sample adapter plate can be used in conventional porosity sample chambers using conventional pressure ramps and test modes, as well as the dynamic test systems and modes described herein. A typical sample test mesh has an outer diameter of 25 mm, with the flow area approximately equal to the outer diameter. Reference FIG. 20A An exemplary sample test net with an outer diameter of 25 mm but an effective flow diameter of only about 5 mm is presented. The reduced flow area of ​​the exemplary sample test net offers an advantage, as flow rate is proportional to area, making it easier to apply the high pressure required to vent small orifices. The larger outer diameter also advantageously provides sufficient upper surface area for O-ring applications. The illustrated sample adapter plate can be advantageously used to test small-orifice (high-pressure) samples to achieve the desired high pressure while restricting flow.

[0100] FIG. 21 An embodiment of a sample adapter plate is shown, illustrating a plate component for receiving filter samples. In this embodiment, an exemplary plate component has a central hole and an O-ring, the central hole being configured to operatively receive a woven test mesh filter sample positioned in a stacked relationship to a lower fine mesh sieve, the O-ring being used to seal the hole for testing. An optional upper coarse sieve is also shown, which can be applied to the upper surface of the woven test mesh filter sample. In this optional aspect, and not limited thereto, the upper coarse sieve may preferably be used when the mesh filter sample contains large-pore samples (e.g., pores larger than about 100 μm) or when improved dry curve behavior is desired.

[0101] Those skilled in the art will understand that woven test mesh filter samples can be formed from interwoven polymer monofilaments, such as, but not limited to, polyester interwoven mesh filter samples. Such interwoven mesh filter samples are available in a variety of sizes specified by the mesh opening size (µ) and are suitable for applications across multiple industries. These interwoven mesh filters possess excellent qualities such as corrosion resistance and moisture resistance, durability, and resilience because the monofilament fibers are woven with tight tolerances, resulting in uniform pore size, superior strength, and dimensional stability.

[0102] However, it is worth noting that conventional interwoven mesh filters can produce gaps with increased porosity in areas close to the overlap of monofilaments, because the corresponding monofilaments are not physically connected at the corresponding points of overlap (other than the nominal force exerted by the corresponding monofilaments due to the interwoven nature of the formed mesh filter). These gaps may adversely affect the accuracy of test results for the formed interwoven mesh filter samples.FIG. 23A and 23B A micrograph of an exemplary woven test filter sample is shown. FIG. 23A A micrograph of a 70 μm woven mesh filter (measured at 65 μm) is shown, and FIG. 23B A micrograph of a 53 μm woven mesh filter (measured at 50 μm) is shown.

[0103] Therefore, in another respect, FIG. 22 The diagram illustrates an embodiment of a test stack profile for locating holes in an adapter plate. In this embodiment, the test stack may include a woven test mesh filter sample configured to be positioned between an upper fine mesh screen and a lower fine mesh screen. In operation, biasing devices, such as O-rings, may be applied to ensure that the formed test stack is in a compressed state, thereby compressing the fibers forming the woven test mesh filter sample together to form a test sample with a more uniform porosity.

[0104] Now for reference FIGS. 24-27 It shows, for example FIG. 22 A graphical illustration of the test results for an exemplary test stack profile is shown. For example, in FIG. 24 and 25 In this process, a 53 μm woven test mesh filter sample is positioned between identical upper and lower fine mesh screens with 250 μm pores. As shown in the figure, the wetted sample is tested in "A" and multiple repeated runs ("B", "C", "D", "E") are run multiple times without rewetting. As shown in "A", the sample is placed... FIG. 22 The exemplary test stack profile shown yields a significantly smaller FBP / BP with excellent accuracy (0.1-0.2% RSD).

[0105] Similarly, and refer to FIG. 26 and 27 It presented as FIG. 22Graphical illustration of the test results for the exemplary test stack profile formed as shown in AE. In this example, a 70 μm woven polyester test filter sample is positioned between the same upper and lower fine mesh screens formed with (250 μm pores). As shown, test “A” with a wetted sample and multiple repeated runs (“B”, “C”, “D”, “E”) are run multiple times without rewetting. As shown, the test using a 70 μm polyester mesh and sample plates (250 μm pores) positioned above and below the test mesh filter shows a close grouping of FBP and BP (0.1–0.2% RSD). Additionally, in the exemplary sample test, the bubble point pore size (average: 95.03 μm) is closer to the pore size calculated based on the thread diameter and pitch (103.02 μm) than the nominal manufacturer's pore size (70 μm).

[0106] In another embodiment, it is conceivable that the test filter sample can be used in a calibration system, wherein the test filter sample can be used in a conventional porosity sample chamber using conventional pressure ramps and test modes, as well as the dynamic test systems and modes described herein. In this respect, and not limited to this, the test filter sample can be configured to be housed within a central hole in a plate member. The test filter sample can have a first plurality of holes and a second plurality of holes, the first plurality of holes having a minimum pore diameter, and the second plurality of holes having a minimum pore diameter greater than the minimum pore diameter of the first plurality of holes.

[0107] In one embodiment, but not limited to, it is envisioned that the first plurality of holes and the second plurality of holes may be laser-drilled microvias. Optionally, in another embodiment, but not limited to, it is envisioned that the test filter sample may be formed from a track-etched film defining the first plurality of holes. In this respect, the second plurality of holes may be laser-drilled microvias into the track-etched film.

[0108] For example, but not limited to, the minimum aperture of the first plurality of holes can be less than 2.0 μm, preferably less than 1.5 μm, more preferably less than 1.0 μm, and still more preferably less than 0.5 μm. For example, but not limited to, the minimum aperture of the second plurality of holes can be greater than 2.0 μm, preferably greater than 4.0 μm, and more preferably greater than 6.0 μm. In other optional embodiments, but not limited to, it is conceivable that the minimum aperture of each hole in the first plurality of holes is less than 2.0 μm, and the minimum aperture of each hole in the second plurality of holes is greater than 2.0 μm.

[0109] Furthermore, it is conceivable that the size of the holes forming the first plurality of holes will exceed the size of the holes forming the second plurality of holes, reaching at least X times the size of the holes forming the second plurality of holes. In this respect, it is conceivable that X can be at least 2, at least 3, at least 5, or at least 10. Furthermore, it is conceivable that the number of holes forming the first plurality of holes will exceed the number of holes forming the second plurality of holes, reaching at least Y times the number of holes forming the second plurality of holes. In this respect, it is conceivable that Y can be at least 10, at least 25, at least 50, or at least 100. It is further conceivable that the first plurality of holes and the second plurality of holes will be arranged in corresponding arrays, wherein the corresponding first plurality of holes and second plurality of holes are spaced apart from adjacent similar holes at a uniform distance.

[0110] In an optional embodiment, the test filter sample may further define at least one distinct pore, which may be a laser micropore drilled into a track-etched film. In this respect, the corresponding aperture and location of the at least one distinct pore may be operator-specified. In another aspect, it is conceivable that the at least one distinct pore may have an aperture different from that of a corresponding first or second plurality of pores.

[0111] In one implementation and reference FIG. 28 An adjustable sample plate assembly 200 can be provided, which is configured to accommodate a relatively thick height ( t Test filter sample 202. Such a sample adjustable sample plate assembly 200 for test filter samples can be used in a conventional porosity sample chamber using conventional pressure ramps and test modes, as well as the dynamic test systems and modes described herein. Conventionally, relatively thick filter samples (e.g., having a cross-sectional thickness of at least 2 mm, at least 4 mm, at least 6 mm, at least 8 mm, or at least 10 mm). t The sample is difficult to test because it is difficult to determine the appropriate size of the spacer to ensure proper compression of the O-ring 220 against the peripheral edge 204 of the upper surface 206 of the test filter sample without damaging the test sample (due to excessively high applied compressive force) or allowing leakage through the O-ring during the high-pressure portion of the test run. In this embodiment, it is conceivable to use a hinged or sliding seal assembly 210 configured to apply a desired level of bias to the O-ring 220 to ensure proper operative positioning of the O-ring against the peripheral edge 204 of the test filter sample, which is positioned within the test hole 212 of the sample plate assembly. On one hand, the hinged or sliding seal assembly 210 may include a dial-in or screw-type assembly 214 configured to apply a desired level of bias force to the O-ring 220. Optionally, and as FIG. 29As shown, the articulated or sliding seal assembly 210 may include an automatically adjustable spring or similar compression-based system 216 configured to apply a desired degree of bias force on the O-ring.

[0112] In one implementation and reference FIG. 29 The inlet side 302 of the test chamber 300 may have a pressure-reducing safety cover 310, which is configured to allow an operator to open the cover 310 when pressurizing the chamber 300 to allow safe release of pressure from the interior of the chamber 300. Such an exemplary pressure-reducing cover can be configured for use with conventional porosity sample chambers using conventional pressure ramps and test modes, as well as the dynamic test systems and modes described herein. In one embodiment, the pressure-reducing safety cover 310 has a circumferential wall 312 configured to be threadedly connected to a complementary threaded circumferential wall 314 in a throat 316 that is in fluid communication with the interior volume 301 of the sample chamber 300 into which a wetted pore sample can be mounted for testing. The cover 310 has a top member 320 having an upper surface 322 and a lower surface 324. As shown, the circumferential wall 312 is connected to the lower surface 324 of the top member 320 near the circumferential edge 326 of the top member, and extends distally from the lower surface 324 substantially transverse to the plane of the top member.

[0113] As shown in the figure, the first flow line 330 is connected to an inlet port 332 defined on the upper surface 332 of the top member of the cap. During operation, it should be understood that as the pressure within the internal volume increases during the test method described herein, the threaded cap / throat will be under increased pressure. As will be understood, during operation, when the cap is fully screwed onto the complementary throat into the sealed position, the upper edge surface 317 of the throat 316 will seal against a portion of the lower surface 234 of the top member 320 of the cap.

[0114] In the implementation and as FIGS. 30A-30D As shown in Figures 31A-31D, it is conceivable that the cover 310 may define at least one cover recess 340, which extends from the distal edge of the threaded portion of the cover to approach the lower surface of the top member. As shown, the at least one cover recess 340 is spaced apart from the end of the thread near the lower surface of the top member. The at least one cover recess 340 extends transversely to the plane of the top member and may extend inwardly to the depth of the cover's tread. For example, and not limited to, the at least one cover recess 340 may have a semi-circular, V-shaped, U-shaped, etc.

[0115] In one exemplary embodiment, the at least one cover recess 340 includes a plurality of cover recesses 340 that may be equidistant from each other. Further still, in an exemplary non-limiting example, the plurality of cover recesses 340 may include four spaced-apart cover recesses.

[0116] In an embodiment, the throat 316 may be envisioned to have a bottom member 350 having a top surface 352 and a bottom surface 354. As shown, a circumferential wall 356 of the bottom member extends from the top surface of the bottom member near its circumferential edge 351 and extends distally from the top surface substantially transverse to the plane of the bottom member. As shown, the throat 316 may define at least one throat groove 360 ​​extending from the proximal edge of the threaded circumferential wall portion of the throat to approach the top surface of the bottom member. As shown, the at least one throat groove 360 ​​is spaced apart from the end of a thread near the top surface of the bottom member. The at least one throat groove 360 ​​extends transversely to the plane of the bottom member and may extend inwardly to the depth of the thread tread. For example, and not limited to, the at least one threaded groove 360 ​​may be semi-circular, V-shaped, U-shaped, etc.

[0117] In one embodiment, the cap 310 and the throat 316 have an equal number of corresponding at least one cap recess 340 and at least one throat recess 360. Further, it is conceivable that if the cap and throat each have corresponding plurality of gap recesses and plurality of throat recesses, the spacing between the corresponding plurality of gap recesses and plurality of throat recesses can be equidistant, thereby allowing the corresponding plurality of gap recesses and plurality of throat recesses to be positioned in an overlapping relationship to allow for the selective formation of a plurality of flow conduits.

[0118] During operation, as the cap 310 is selectively rotated relative to the throat 316 from the sealed position, the cap 310 can rotate at an angle until the at least one cap recess 340 and the at least one throat recess 360 (correspondingly, a plurality of gap recesses and a plurality of throat recesses) are positioned in an overlapping relationship. In this position, the cap recess and the throat recess form a fluid conduit that communicates with the pressurized internal volume of the sample chamber and atmospheric fluid, while resisting separation of the cap from the throat due to the still threaded positioning of the cap and throat. Furthermore, in this position, fluid flowing through the formed fluid conduit can produce a tone to notify the operator that fluid is escaping from the sample chamber.

[0119] In this embodiment, an apparatus for dynamically determining the permeability of porous solids is described, the apparatus comprising a sample chamber, a first flow line, at least one gas source, at least one pressure measuring device, at least one mass flow meter, and a control system: the sample chamber defines an internal volume including a sample holder for holding a wetted porous solid sample. The internal volume of the sample chamber defines an inlet side and an outlet side, the two sides being separated by the sample holder, wherein the outlet side is in fluid communication with the atmosphere.

[0120] The first flow line is in volumetric fluid communication with the inlet side of the sample chamber, and the at least one gas source is in fluid communication with the first flow line. The at least one pressure measuring device is configured to sense the pressure of the gas supplied to the first flow line, and the at least one mass flow meter is configured to sense the mass flow rate of the pressurized gas supplied to the first flow line.

[0121] The control subsystem includes a processor that communicates with the at least one pressure measuring device and the at least one mass flow meter. In operation, the processor is configured to selectively adjust the pressure of the gas supplied to the porous solid sample positioned in the sample chamber and the mass flow rate of the gas supplied as a pressurized gas flow to the porous solid sample in response to sensed gas pressure and sensed mass flow rate of the supplied pressurized gas flow, to maintain control over the gas pressure and mass flow rate according to a test protocol pressure ramp. Further, in operation, the processor is configured to dynamically adjust the pressure ramp rate of the gas supplied to the porous solid sample in response to an increase in the sensed mass flow rate of the pressurized gas, to exponentially increase the pressure ramp rate, thereby increasing the resolution of the determination of the pore size in the wetted porous sample.

[0122] In an embodiment and in operation, the processor is further configured to dynamically adjust the pressure ramp rate of the gas supplied to the porous solid sample in response to a decrease in the mass flow rate of the sensed pressurized gas, thereby increasing the pressure ramp rate exponentially to increase resolution, and thus increasing the pressure ramp rate exponentially as the sensed flow rate decreases.

[0123] In implementation and operation, the test scheme pressure ramp may include a linear pressure ramp scheme until the bubble point of the wetted porous solid sample is reached. At this point, upon determining that the bubble point has been reached, the processor is configured to deviate from the linear pressure ramp scheme by dynamically changing the linear slope of the pressure change to exponentially slow the increase of the pressure ramp, thereby approaching a constant pressure, which is a function of the gas flow rate change.

[0124] In implementation and operation, the test scheme pressure ramp may include a pressure step ramp scheme until the bubble point of the wetted porous solid sample is reached. At this point, upon determining that the bubble point has been reached, the processor is configured to deviate from the pressure step ramp scheme by dynamically changing the slope of the pressure change to exponentially slow the increase of the pressure ramp, thereby approaching a constant pressure, which is a function of the gas flow rate change.

[0125] In another embodiment, the test scheme pressure ramp allows the pressure to ramp up at a rapid rate while the percentage change in mass flow rate per unit time through the wetted porous solid sample is small, wherein the rate of pressure change increases toward the maximum permissible rate of pressure change until the bubble point is reached. In this case, the process is configured to dynamically reduce the rate of pressure change according to an exponential factor based on the percentage change in mass flow rate per unit time. In another embodiment, the exponential factor is selectable, allowing the rate of pressure change to ramp up at a slower rate until the bubble point is reached, and subsequently can be dynamically adjusted to remain nearly zero throughout the pore opening period of the wetted porous solid sample.

[0126] In another alternative implementation and during operation, upon determining that the bubbling point has been reached, the processor can be configured to apply a user-selected factor N to determine the test stop time, which is less than the total nominal time of the complete test plan. Exemplarily, the factor N is at least 2.

[0127] Optionally, in embodiments and in operation, the processor is configured to dynamically increase the pressure ramp rate as the mass flow rate changes, and dynamically decrease the pressure ramp rate as the mass flow rate changes. In embodiments and in operation, the processor is configured to apply a set of user-adjustable parameters to control the sensitivity of the pressure ramp to changes in mass flow rate, and to apply a resolution parameter to control the pressure change rate. In another embodiment and in operation, the processor is configured to dynamically adjust the applied pressure rate based on a set of user-adjustable parameters, which includes at least one of the following three: a maximum pressure ramp rate; a resolution parameter to control the ramp rate deceleration; and a sensitivity parameter to control how sensitive the pressure change rate is to changes in the gas flow rate.

[0128] In another alternative embodiment and in operation, the sample component may include an adapter plate having a plate member configured with a central hole, the size and shape of which are operatively configured to receive the wetted porous solid sample. In various respects, the plate member has a first outer diameter, wherein the central hole has a second diameter smaller than the first outer diameter.

[0129] In another alternative embodiment and in operation, the wetted porous solid sample may include a woven mesh filter sample.

[0130] In another alternative embodiment and during operation, the woven mesh filter sample can be positioned in a stacked relationship, stacked on top of the lower mesh screen. In another exemplary aspect, a biasing device can be applied to a portion of the upper surface of the woven mesh filter sample and operatively seal the woven mesh filter sample within the central hole. Optionally, the woven mesh filter sample can be positioned in a stacked relationship, stacked below the upper mesh screen and above the lower mesh screen, which allows the biasing device to be applied to a portion of the upper surface of the upper mesh screen to operatively seal the woven mesh filter sample within the central hole.

[0131] In another optional embodiment and in operation, the wetted porous solid sample may include a test filter sample having a first plurality of pores and a second plurality of pores, the first plurality of pores having a minimum pore diameter of less than 1.0 μm, and the second plurality of pores having a minimum pore diameter greater than the minimum pore diameter of the first plurality of pores. In an exemplary aspect, the minimum pore diameter of the second plurality of pores is greater than 2.0 μm. Optionally, the number of pores forming the first plurality of pores may exceed the number of pores forming the second plurality of pores, and reach at least Y times the number of pores forming the second plurality of pores. For example, and not limited thereto, the factor Y is at least 10.

[0132] In an embodiment, this document describes a method for determining the permeability of a porous solid, the method comprising: mounting a wetted porous solid sample within an internal volume of a sample chamber; and selectively adjusting the pressure of a gas supplied to the porous solid sample positioned within the sample chamber and the mass flow rate of the gas supplied to the porous solid sample as a pressurized gas flow to maintain control over the pressure and mass flow rate of the gas according to a pressure ramp of a test protocol. In an embodiment and in operation, the method further includes dynamically adjusting the pressure ramp rate of the gas supplied to the porous solid sample in response to an increase in the mass flow rate of the sensed pressurized gas, so as to exponentially increase the pressure ramp rate, thereby increasing the resolution of the determination of the pore size in the wetted porous sample.

[0133] Various embodiments of the porosity measuring and analyzing apparatus have been described above, and the disclosed systems and methods have been provided to illustrate necessary and optional features and functions. Alternatives or modifications that may be conceived by those skilled in the art without departing from the principles of the invention as covered by the appended claims may be functionally equivalent.

Claims

1. An apparatus for dynamically determining the permeability of porous solids, characterized in that, The device includes: A sample chamber defining an internal volume including a sample holder for holding a wetted porous solid sample, wherein the internal volume of the sample chamber defines an inlet side and an outlet side separated by the sample holder, wherein the outlet side is in fluid communication with the atmosphere. A first flow line is connected to the internal volumetric fluid of the sample chamber at the inlet side. At least one gas source, the at least one gas source being in fluid communication with the first flow line; At least one pressure measuring device, the at least one pressure measuring device being configured to sense the pressure of the gas supplied to the first flow line; At least one mass flow meter, the at least one mass flow meter being configured to sense the mass flow rate of pressurized gas supplied to the first flow line; and A control subsystem comprising a processor communicating with the at least one pressure measuring device and the at least one mass flow meter, wherein the processor selectively adjusts the pressure of the gas supplied to the porous solid sample located in the sample chamber and the mass flow rate of the gas supplied as a pressurized gas flow to the porous solid sample in response to sensed gas pressure and sensed mass flow rate of the supplied pressurized gas flow, to maintain control of the gas pressure and mass flow rate according to a test protocol pressure ramp, and wherein the processor dynamically adjusts the pressure ramp rate of the gas supplied to the porous solid sample in response to an increase in sensed mass flow rate of the pressurized gas, to exponentially increase the pressure ramp rate, thereby increasing the resolution of the determination of the pore size in the wetted porous sample.

2. The device according to claim 1, characterized in that, The processor dynamically adjusts the pressure ramp rate of the gas supplied to the porous solid sample in response to a decrease in the sensed mass flow rate of the pressurized gas, thereby increasing the pressure ramp rate exponentially to increase the resolution, and thus increasing the pressure ramp rate exponentially as the sensed flow rate decreases.

3. The device according to claim 1, characterized in that, The test scheme includes a linear pressure ramp scheme until the bubble point of the wetted porous solid sample is reached, and wherein, upon determining that the bubble point has been reached, the processor deviates from the linear pressure ramp scheme by dynamically changing the linear slope of the pressure change to exponentially slow down the increase of the pressure ramp, thereby approaching a constant pressure, which is a function of the gas flow rate change.

4. The device according to claim 3, characterized in that, The processor is configured to dynamically increase the pressure ramp rate as the rate of change of mass flow decreases, and dynamically decrease the pressure ramp rate as the rate of change of mass flow increases.

5. The device according to claim 3, characterized in that, The processor uses a set of user-adjustable parameters to control the sensitivity of the pressure ramp to changes in mass flow rate, and uses resolution parameters to control the rate of pressure change.

6. The device according to claim 4, characterized in that, The processor further dynamically adjusts the applied pressure rate based on a set of user-adjustable parameters, which include at least one of the following three: a maximum pressure ramp rate; a resolution parameter for controlling the ramp rate deceleration; and a sensitivity parameter for controlling how sensitive the pressure change rate is to changes in the gas flow rate.

7. The device according to claim 1, characterized in that, The test scheme includes a pressure stepping slope scheme until the bubble point of the wetted porous solid sample is reached, and wherein, upon determining that the bubble point has been reached, the processor deviates from the pressure stepping slope scheme by dynamically changing the slope of the pressure change to exponentially slow down the increase of the pressure slope, thereby approaching a constant pressure, which is a function of the gas flow rate change.

8. The device according to claim 7, characterized in that, The processor is configured to dynamically increase the pressure ramp rate as the rate of change of mass flow decreases, and dynamically decrease the pressure ramp rate as the rate of change of mass flow increases.

9. The device according to claim 7, characterized in that, The processor uses a set of user-adjustable parameters to control the sensitivity of the pressure ramp to changes in mass flow rate, and uses resolution parameters to control the rate of pressure change.

10. The device according to claim 9, characterized in that, The processor further dynamically adjusts the applied pressure rate based on a set of user-adjustable parameters, which include at least one of the following three: a maximum pressure ramp rate; a resolution parameter for controlling the ramp rate deceleration; and a sensitivity parameter for controlling how sensitive the pressure change rate is to changes in the gas flow rate.

11. The device according to claim 2, characterized in that, The test scheme's pressure ramp allows the pressure to rise rapidly while the percentage change in mass flow rate per unit time through the wetted porous solid sample is small, wherein the rate of pressure change increases toward the maximum permissible rate of pressure change until the bubble point is reached, after which the rate of pressure change dynamically decreases according to an exponential factor based on the percentage change in mass flow rate per unit time.

12. The device according to claim 11, characterized in that, The exponential factor is selectable, causing the rate of pressure change to rise at a slower rate until the bubble point is reached, and is subsequently dynamically adjusted to remain nearly zero throughout the pore opening of the wetted porous solid sample.

13. The device according to claim 1, characterized in that, When the processor determines that the bubble point has been reached, it applies a user-selected factor N to determine the test stop time, which is less than the total nominal time of the complete test plan.

14. The device according to claim 13, characterized in that, The factor N is at least 2.

15. The device according to claim 1, characterized in that, The sample component includes an adapter plate having a plate member configured with a central hole whose size and shape are operablely set to accommodate the wetted porous solid sample.

16. The device according to claim 15, characterized in that, The plate member has a first outer diameter, wherein the central hole has a second diameter, the second diameter being smaller than the first outer diameter.

17. The device according to claim 16, characterized in that, The wetted porous solid sample includes a woven mesh filter sample.

18. The device according to claim 17, characterized in that, The woven mesh filter sample is positioned in a stacked relationship to be stacked on top of a lower mesh screen. The device further includes a biasing device applied to a portion of the upper surface of the woven mesh filter sample and configured to seal the woven mesh filter sample within the central hole.

19. The device according to claim 17, characterized in that, The woven mesh filter sample is positioned in a stacked relationship, stacked below the upper mesh screen and above the lower mesh screen. The device further includes a biasing device applied to a portion of the upper surface of the upper mesh screen and configured to seal the woven mesh filter sample within the central hole.

20. The device according to claim 15, characterized in that, The wetted porous solid sample includes a test filter sample, wherein the test filter sample has a first plurality of pores and a second plurality of pores, the first plurality of pores having a minimum pore diameter, the second plurality of pores having a minimum pore diameter, and the minimum pore diameter being greater than the minimum pore diameter of the first plurality of pores.

21. The device according to claim 20, characterized in that, The minimum aperture of each of the first plurality of holes is less than 2.0 μm, and the minimum aperture of each of the second plurality of holes is greater than 2.0 μm.

22. The device according to claim 20, characterized in that, The number of holes forming the first plurality of holes will exceed the number of holes forming the second plurality of holes, and will reach at least Y times the number of holes forming the second plurality of holes.

23. The device according to claim 22, characterized in that, The factor Y is at least 10.

24. A method for determining the permeability of porous solids, characterized in that, The method includes: A wetted porous solid sample is installed inside the sample chamber. The pressure of the gas supplied to the porous solid sample positioned in the sample chamber and the mass flow rate of the gas supplied to the porous solid sample as a pressurized gas flow are selectively adjusted to maintain control of the gas pressure and mass flow rate according to the pressure ramp of the test protocol; and In response to an increase in the mass flow rate of the sensed pressurized gas, the pressure ramp rate of the gas supplied to the porous solid sample is dynamically adjusted to exponentially increase the pressure ramp rate, thereby increasing the resolution of the determination of the pore size in the wetted porous sample.

25. The method according to claim 24, characterized in that, The method further includes dynamically adjusting the pressure ramp rate of the gas supplied to the porous solid sample in response to a decrease in the mass flow rate of the sensed pressurized gas, so as to increase the pressure ramp rate exponentially to increase the resolution, thereby increasing the pressure ramp rate exponentially as the sensed flow rate decreases.

26. The method according to claim 24, characterized in that, The method further includes applying a linear pressure ramp scheme until the bubble point of the wetted porous solid sample is reached, and upon reaching the bubble point, deviating from the linear pressure ramp scheme by dynamically changing the linear slope of the pressure change to exponentially slow down the increase of the pressure ramp, thereby approaching a constant pressure, the constant pressure being a function of the gas flow rate change.

27. The method according to claim 24, characterized in that, The method further includes applying a pressure stepping ramp scheme until the bubble point of the wetted porous solid sample is reached, and upon reaching the bubble point, deviating from the pressure stepping ramp scheme by dynamically changing the slope of the pressure change to exponentially slow down the increase of the pressure ramp, thereby approaching a constant pressure, which is a function of the gas flow rate change.

28. The method according to claim 24, characterized in that, The method further includes dynamically reducing the pressure change rate based on an exponential factor of the percentage change in mass flow rate per unit time when the bubble point is reached.

29. The method according to claim 28, characterized in that, The exponential factor is selectable, causing the rate of pressure change to rise at a slower rate until the bubble point, and then dynamically adjusted to remain almost zero throughout the pore opening of the wetted porous solid sample.

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