Foam fire extinguishing agent mixer

Abstract

To provide a fire foam mixer capable of mixing water and fire foam at an appropriate ratio regardless of pressure of a water source.SOLUTION: A fire foam mixer according to the present invention, the fire foam mixer is used for a pump proportioner-type foam fire extinguishing system. The fire foam mixer includes a chemical suction chamber 14c communicated with the outside, provided between a primary-side throat 14a and a secondary-side throat 14b of a Venturi tube, where it is defined that 1<(minimum diameter D2 of the secondary-side throat 14b) / (minimum diameter D1 of the primary-side throat 14a)<3.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a foam mixer for mixing a fire extinguishing foam with water, and is suitable for use in a fire engine. [Background technology]

[0002] Foam fire extinguishing systems have been known as fire extinguishing systems mounted on fire engines. In these systems, a foam fire extinguishing agent is mixed with water in a predetermined ratio to form an aqueous foam fire extinguishing agent solution, which is then foamed in a foaming device and then released at the source of the fire to extinguish oil fires and other hazardous material fires.

[0003] In a foam fire extinguishing system, a foam extinguishing agent mixer is used to mix the foam extinguishing agent with water at a predetermined ratio. The foam extinguishing agent mixer has an agent suction chamber connected to the outside between the primary throat and the secondary throat of the Venturi pipe. Foam fire extinguishing agent mixer are known (see, for example, Patent Documents 1 and 2). In these mixers, when water is supplied from the primary throat, the chemical suction chamber becomes negative pressure, and the foam extinguishing agent is sucked in and mixed with the water, becoming an aqueous foam extinguishing agent solution that is discharged from the secondary throat.

[0004] A known foam fire extinguishing system using a foam mixer is the pump proportioner type shown in Figure 1. This foam fire extinguishing system has a pump 2 installed in a water supply pipe 1, which can be driven to send water from a water source to the discharge side. Also, bypass pipes 3 are connected to the discharge and suction sides of the pump 2. When mixing foam fire extinguishing agents to extinguish a fire, the pump 2 is driven, and then an on-off valve 3a is opened to circulate water through the bypass pipe 3. A Venturi pipe 4 is installed in the bypass pipe 3, and an agent supply pipe 5 is connected between the primary throat 4a and the secondary throat 4b to supply foam fire extinguishing agents.

[0005] In a pump proportioner type foam fire extinguishing system, water from a water source is sent to the discharge side by driving pump 2 through water supply pipe 1, and by opening on-off valve 3a, a portion of the discharged water enters bypass pipe 3 and circulates. Then, foam extinguishing agent is sucked in by Venturi pipe 4 located midway through bypass pipe 3 and mixed with water, becoming an aqueous foam extinguishing agent solution, which is injected into water supply pipe 1 from the suction side of pump 2 and sent to the discharge side. After foaming in the foaming device, the foam is released toward the source of the fire.

[0006] In a pump proportioner type foam fire extinguishing system, the Venturi pipe 4 is installed in the bypass pipe 3 instead of in the water supply pipe 1, so the foam solution can be pumped without sacrificing pump capacity (water head and water supply volume). This has the advantage that the spray pressure from the nozzle at the tip can be ensured even if there is a certain degree of pressure loss in the piping and hose when pumping the foam solution. Another advantage is that there is no need to install a separate power source to inject the foam solution. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Utility Model Application Publication No. 55-037604 [Patent Document 2] Japanese Utility Model Application Publication No. 04-70052 Summary of the Invention [Problem to be solved by the invention]

[0008] However, with the conventional foam mixers, changes in the supply pressure from the water source can cause problems, such as the inability to mix water and foam or a change in the mixing ratio, resulting in a deviation from the optimal ratio for firefighting. This is particularly true for fire trucks, where various water sources, such as onboard storage tanks and reservoirs (where no pressure is applied) and high-pressure water from fire hydrants, make it difficult to achieve the optimal mixing ratio. Furthermore, pressure loss in the bypass pipe can also affect the optimal mixing ratio. Positioning a pump proportioner to minimize this effect can also make it difficult to operate the adjustment valve that controls the mixing ratio during firefighting activities. The present invention addresses these issues and aims to provide a foam mixer that can mix water and foam at the optimal ratio regardless of the pressure of the water source. [Means for solving the problem]

[0009] The present inventors have conducted extensive research into the above-mentioned problems with pump proportioner foam fire extinguishing systems, and have found that the above-mentioned problems can be solved by setting the ratio of the minimum diameter D1 of the primary throat of the Venturi pipe to the minimum diameter D2 of the secondary throat in a predetermined range in a foam fire extinguishing agent mixer used in a pump proportioner foam fire extinguishing system, thereby completing the present invention.

[0010] In other words, the foam fire extinguishing agent mixer of the present invention is a foam fire extinguishing agent mixer used in a pump proportioner type foam fire extinguishing device, and is characterized in that a chemical suction chamber communicating with the outside is provided between the primary throat and secondary throat of the Venturi pipe, and the ratio is 1<(minimum diameter D2 of secondary throat) / (minimum diameter D1 of primary throat)<3.

[0011] According to the inventor's test results, if the value of (minimum diameter D2 of the secondary throat) / (minimum diameter D1 of the primary throat) is less than 1, the agent suction chamber will not become negative pressure, and foam extinguishing agent will not be able to be supplied. For this reason, it is recommended to set the value of (minimum diameter D2 of the secondary throat) / (minimum diameter D1 of the primary throat) to 1 or more to supply the agent. Agent The suction chamber must be under negative pressure. In addition, when the supply pressure of the water source is high, such as with a pressurized fire hydrant, the pressure downstream of the secondary throat connected to the pump suction side also rises, Agent The suction chamber will not create negative pressure, making it impossible to suck in the foam extinguishing agent. For this reason, it is advisable to increase the value of (minimum diameter D2 of the secondary throat) / (minimum diameter D1 of the primary throat), but if this value is 3 or greater, the negative pressure generated in the agent suction chamber will weaken, making it impossible to stably suck in the foam extinguishing agent. Therefore, the ratio must be 1 < (minimum diameter D2 of the secondary throat) / (minimum diameter D1 of the primary throat) < 3. A more preferable range is 1.2 < (minimum diameter D2 of the secondary throat) / (minimum diameter D1 of the primary throat) < 2.

[0012] Even if the supply pressure from the water source is high, Agent To maintain a negative pressure in the suction chamber, it is preferable to increase the pressure upstream of the primary throat of the Venturi tube, which is connected to the discharge side of the pump. The pressure upstream of the primary throat of the Venturi tube is roughly equivalent to the operating pressure of the foam generator or water discharge device connected to the discharge side of the pump, and its value is generally in the range of 0.4 MPa to 1.4 MPa. When the pressure upstream of the primary throat is 0.4 MPa, the preferable range for maintaining a negative pressure in the agent suction chamber is 1.2 < (minimum diameter D2 of the secondary throat) / (minimum diameter D1 of the primary throat) < 2. Within this range, even if the pressure upstream of the primary throat is 0.4 MPa, foam agent can be sucked in as long as the pressure downstream of the secondary throat is less than 0.2 MPa.

[0013] medicine Agent A drug supply pipe communicating with the outside is connected to the suction chamber, Drug supply pipePreferably, the fire extinguishing device is provided with an adjustment valve that can adjust the flow rate of the chemical solution. This makes it possible to adjust the mixture ratio of water and foam fire extinguishing agent to a more appropriate value. In this case, it is preferable that the valve element of the adjustment valve is connected to an adjustment dial via a universal joint, and that the adjustment valve can be adjusted by turning the adjustment dial. In this case, the adjustment dial can be adjusted even from a position away from the adjustment valve, so that the worker can easily adjust the mixture ratio from a position that is convenient for them. [Brief explanation of the drawings]

[0014] [Figure 1] 1A to 1C are schematic diagrams of a proportioner-type foam fire extinguishing device in various modes of use. [Figure 2] FIG. 1 is a schematic diagram of a foam fire extinguishing device using the foam fire extinguishing agent mixer of Example 1. [Figure 3] FIG. 2 is a partial cross-sectional view of the fire foam mixer of Example 1. [Figure 4] FIG. 1 is a plan view of a fire foam mixer according to a first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, specific examples of the present invention will be described. Example 1 The foam extinguishing agent mixer of Example 1 is installed in a pump proportioner-type foam fire extinguishing system mounted on a fire truck for the purpose of mixing foam extinguishing agent and water. As shown in FIG. 2 , this foam fire extinguishing system 10 has a pump 12 installed in a water supply pipe 11, and by driving the pump 12, water can be sent to the discharge side from various water sources. Water sources that can be used include a water storage tank mounted on the fire truck, a fire hydrant near the fire scene, and water from rivers, lakes, and water tanks. In addition, bypass pipes 13 are connected to the discharge and suction sides of the pump 12 to the water supply pipe 11. When foam firefighting is performed, after driving the pump 12, an on-off valve 13a installed in the bypass pipe 13 is opened, allowing a portion of the water in the water supply pipe 11 to flow into the bypass pipe 13 on the outflow side of the pump 12 and circulate through the foam extinguishing agent mixer 14.

[0016] The foam extinguishing agent mixer 14 of Example 1 is provided midway through the bypass pipe 13 and forms a Venturi pipe. As shown in Fig. 3, an agent suction chamber 14c communicating with the outside is provided between the primary throat 14a and secondary throat 14b of the foam extinguishing agent mixer 14, and a foam extinguishing agent supply pipe 15 for sucking in the foam extinguishing agent is connected to the agent suction chamber 14c. The foam extinguishing agent supply pipe 15 is connected to an agent storage tank 16 (Fig. 2) that stores the foam extinguishing agent. The pipe diameter of the primary throat 14a tapers downstream, with a minimum diameter D1. The secondary throat 14b tapers upstream, with a minimum diameter D2.

[0017] 4, a lift-type or rotary adjustment valve 17 is provided between the foam extinguishing agent mixer 14 and the foam extinguishing agent supply pipe 15, which allows adjustment of the amount of foam extinguishing agent to be sucked in. A universal joint 18 is connected to the adjustment valve 17, and the other end of the universal joint 18 is connected to a rotary adjustment dial 19. By rotating the adjustment dial 19, the universal joint 18 rotates, and a valve element (not shown) inside the adjustment valve 17 moves, changing the flow path area. The adjustment dial 19 is equipped with a scale, and by adjusting the scale, the operator can adjust the mixing ratio of water and foam extinguishing agent to a predetermined value.

[0018] The foam mixture shown in Figure 2 vessel After arriving at the scene of a fire, the fire engine equipped with 10 selects a water source (for example, a fire hydrant, a river, a water tank, or a water tank mounted on the fire engine) depending on the situation at the scene, and then makes the necessary preparations for water supply (such as connecting and extending the hose). Pump 12 is then driven to allow water from the water source to flow into water pipe 11. When performing firefighting activities using foam, an on-off valve 13a provided on bypass pipe 13 is opened to allow some of the water flowing out from pump 12 to flow into bypass pipe 13. The inflowing water enters primary throat 14a of foam fire extinguishing agent mixer 14 shown in FIG. 3, passes through agent suction chamber 14c and secondary throat 14b, is sent to bypass pipe 13, and flows back into water pipe 11 on the suction side of pump 12. Foam extinguishing agent mixer 14 forms a Venturi tube, and when water is passed through it, foam extinguishing agent from chemical storage tank 16 (Fig. 2) flows into chemical suction chamber 14c, where it is mixed with the water to become an aqueous foam extinguishing agent solution, which flows from the suction side of pump 12 through secondary throat 14b and bypass pipe 13 into water pipe 11. Pump 12 then sends the solution again through discharge side water pipe 11 to a foam generator or water discharge device, where the foam or aqueous foam extinguishing agent solution is released toward the source of the fire.

[0019] In the foam extinguishing agent mixer 14 of Example 1 configured as described above, the value of (minimum diameter D2 of secondary throat 14b) / (minimum diameter D1 of primary throat 14a) was changed. As a result, when the value of (minimum diameter D2 of secondary throat 14b) / (minimum diameter D1 of primary throat 14a) was less than 1, negative pressure was not generated in the agent suction chamber 14c, and the foam extinguishing agent could not be sucked in. On the other hand, when the water source has low supply pressure, such as a water tank, if the value of (minimum diameter D2 of secondary throat 14b) / (minimum diameter D1 of primary throat 14a) was set to 1 or more, the foam extinguishing agent could be sucked in. Agent It was found that negative pressure was generated in the suction chamber 14c, and the foam fire extinguishing agent could be sucked in. However, when the water source has a high supply pressure, such as a pressure fire hydrant, the pressure in the downstream area of ​​the secondary throat 14b, which is connected to the suction side of the pump 12, also rises, and the agent can be sucked in. Agent The negative pressure generated in suction chamber 14c also decreases, so to prevent the foam extinguishing agent from being sucked in, it was necessary to make the value of (minimum diameter D2 of secondary throat 14b) / (minimum diameter D1 of primary throat 14a) greater than 1. However, when the value of (minimum diameter D2 of secondary throat 14b) / (minimum diameter D1 of primary throat 14a) becomes 3 or greater, the negative pressure generated in agent suction chamber 14c decreases, making it impossible to stably suck in the foam extinguishing agent.

[0020] Even when the supply pressure from the water source increases, the agent in the foam mixer 14 AgentTo generate negative pressure in the suction chamber 14c, it is preferable to increase the pressure (discharge pressure of the pump 12) when the foam enters the mixer 14. The pressure when the foam enters the mixer 14 is roughly equivalent to the water discharge pressure of the foam generator or water discharge device connected to the discharge side of the pump 12, and its value is roughly in the range of 0.4 MPa to 1.4 MPa. That is, even if the pressure when the foam enters the mixer 14 is 0.4 MPa, a range of 1.2 < (minimum diameter D2 of the secondary throat) / (minimum diameter D1 of the primary throat) < 2 is preferable to create negative pressure in the agent suction chamber 14c. Within this range, even if the pressure upstream of the primary throat 14a is 0.4 MPa, the foam can be sucked in as long as the pressure downstream of the secondary throat 14b is less than 0.2 MPa.

[0021] When using the foam fire extinguishing agent mixer of Example 1 to extinguish a fire with foam, the type and mixing ratio of the foam extinguishing agent can be changed depending on the type of fire and the material being burned. For example, in the case of a general fire involving wood, waste paper, or the like, spraying an aqueous solution containing a small amount of synthetic surfactant foam extinguishing agent mixed in at approximately 0.08 to 0.5% can increase penetration compared to water and improve fire extinguishing efficiency. In addition, in the case of a fire involving hazardous materials such as gasoline or kerosene, spraying an aqueous solution containing a protein foam extinguishing agent or an aqueous film-forming foam extinguishing agent mixed in at approximately 3% can foam and coat the surface of the hazardous material with foam, improving fire extinguishing efficiency.

[0022] The number of foam generators and water discharge devices used and the amount discharged vary depending on the scale of the fire, so the amount flowing through the water pipe 11 also varies, and for small and medium-sized fire engines, it is generally in the range of 100 to 2,400 liters per minute. It is also preferable to adjust the foam extinguishing agent mixture ratio using the adjustment valve 17 so that it is appropriate depending on the type of fire and the material being burned. Specifically, it is preferable to adjust the mixture ratio to 0.08 to 0.5% for general fires and approximately 3% for hazardous material fires, and adjustment is possible within this range.

[0023] Adjustment method using the adjusting valve 17 The suction volume using the regulating valve 17 is adjusted by setting the regulating dial 19 to a predetermined scale position. By turning the regulating dial 19, the valve element inside the regulating valve 17 moves via the universal joint 18, adjusting the amount of foam extinguishing agent suctioned. The scale indicates the amount of foam extinguishing agent solution to be used and the mixing ratio, allowing the operator to easily adjust the mixing ratio of water and foam extinguishing agent. Furthermore, because the valve element inside the regulating valve 17 is connected to the regulating dial 19 via the universal joint 18, it can be operated remotely, improving the flexibility of the installation location of the foam extinguishing agent mixer 14 when designing a fire truck.

[0024] The present invention is not limited to the above-described embodiments and examples, and various modifications within the scope of the claims and within the scope that can be easily conceived by a person skilled in the art are also included in the present invention. [Explanation of symbols]

[0025] 10...Foam fire extinguishing device, 1,11...Water pipe, 2,12...Pump, 3, 13... Bypass pipe, 3a, 13a... On-off valve, 4, 14... Foam extinguishing agent mixer (14a... Primary throat, 14b... Secondary throat, 14c... Agent suction chamber), 5, 15... Foam extinguishing agent supply pipe, 16... Agent storage tank, 17... Adjusting valve, 18...Universal joint, 19...Adjustment dial

Claims

[Claim 1] A foam extinguishing agent mixer for a fire engine used in a pump proportioner type foam fire extinguishing system, a drug suction chamber communicating with the outside is provided between the primary throat and the secondary throat of the Venturi tube, and 1.2<(minimum diameter D2 of the secondary throat) / (minimum diameter D1 of the primary throat)<2; a drug supply pipe communicating with the outside is connected to the drug suction chamber, and the drug supply pipe is provided with an adjustment valve that can adjust the flow rate of the drug solution; A foam fire extinguishing agent mixer for a fire truck, wherein the valve element of the adjustment valve is connected to an adjustment dial via a universal joint, and the adjustment valve can be adjusted by turning the adjustment dial.

Images