[Fire Truck] High fire truck water supply combat effectiveness in chemical fires

Abstract : Analyze the fire extinguishing agent spray form and fire extinguishing agent method in chemical fire. In view of the characteristics of high-ejection fire fighting vehicles, the influences of the working pressure of the boom guns on the boom, the relationship between the pressure and flow of the water supply, and the maximum water supply height for the high fire trucks are analyzed. In response to the issue of water supply security for high-elevation fire trucks, the water supply method and the water supply time node were analyzed, and a method of water supply security was proposed. The results of the study can provide technical support for fire fighting operations in high-level fire engines during chemical fires.

Keywords: petrochemical fires; lifting high fire trucks; water supply pressure; firefighting and rescue

In recent years, chemical fires have occurred frequently, such as the " 7 • 16 " explosion of oil refining installations in Dalian PetroChina No. 7 Plant, " 7 • 18 " fires in Shandong Weifang Qingzhou Tiancheng Chemical Co., Ltd., and " 9 • 8 " Shanghai SECCO chemical plant fires. For chemical fires, the control of fire is extremely important. Fire-fighting squirt guns and foam guns used by fire brigades are difficult to fire in close combat, and they cannot achieve the water flow for cooling treatment. For high fire trucks, the lift height is high and the jet flow rate is high. Such characteristics play an important role in petrochemical fires. In the event of a high fire point, high-power fire fighting vehicles can use their high-altitude combat capabilities to fight petrochemical fires more efficiently, accurately, with less time and effort. Therefore, it is a prerequisite to effectively control fires by giving full play to the combat effectiveness of fire fighting vehicles.

Extinguishing agent job analysis for fire Elevating Fire 1

The term “high fire truck” refers to a fire truck that has a high-level fire extinguishing function or a high-level fire extinguishing and rescue function, and mainly includes a ladder fire truck, an ascending platform fire truck, and a high-elevation fire engine. In the case of petrochemical fires, high fire trucks are mainly used for cooling and extinguishing fires. Water and foam are mainly delivered to the fire by means of vehicle-mounted guns, and high-emission fire engines are used in petrochemical fires. Therefore, the author mentions that high fire engines refer to high-ejection fire engines.

1 . 1 lift fire extinguisher spray form

The high fire trucks are mainly used for extinguishing fires or controlling fires from the outside of the device. When using arm guns to carry out external attack and fire extinguishing, the booms are mainly lifted to the vicinity of the fire point and the fire extinguishers can be extinguished by using the on-board guns. In chemical fires, the cameras and searchlights mounted on the composite cannon at the top of the boom are used to timely and accurately observe the actual situation of the fire, and accordingly, different types of fire extinguishing agent are reasonably selected to remotely control the compound gun at the top of the boom and adjust the fire extinguishing agent. The jet height, angle, and distance increase the accuracy of the extinguishing agent spray and increase the efficiency of the fire extinguishing. In situations where the height of the fire site is high and the controllable range is large, it is necessary to adjust the height of the boom and the spray angle and range of the boom gun.

If the angle of the boom gun needs to be adjusted during high-speed jet fire , it should be operated slowly to avoid damage to the transmission mechanism. In addition, when a high-fire truck is in the process of petrochemical fire fighting, when its boom gun is threatened by high-temperature baking, the driver should immediately start the arm gun self-protection system for protection.

1 . 2 lift high fire trucks for fire extinguishing methods

Lifting fire trucks The on-board guns mainly rely on their own pump systems to provide pressurized fire extinguishing agents to the fire site. When the fire pump systems and foam systems of high fire trucks fail, they can use water hoses to connect the fire water outlets or fire hydrants with water hoses. The external water supply valve of the boom gun can be reliably connected to open the external water supply valve of the boom gun and supply the water directly to the boom gun, that is, the external water supply operation.

Through the 32 rn high lift jet fire water jet operation application performance test analysis, using its own water pump system, the water supply pressure is 1 . When 0 MPa, reached 35 m range artillery fire _ Xi water, a water pressure. At 0 MPa pressure, the fire monitor reached a range of only 30 m . This test shows that when using fire extinguishers to supply fire extinguishing agents to fire sites, when the vehicle has a fire pump system and can be used normally, do not use external water supply.

2 lift high fire trucks for fire extinguishing ability

2 . 1 Effect of Working Pressure of Boom Gun on Boom

When a high fire truck is carrying out a firefighting operation, a momentary impact load is applied to the boom at the moment when the boom opens, and the load is a non-periodic irregular curve. For some special forms of impact loads, rectangular, triangular, sinusoidal, parabolic and other regular curves can be used to describe. The author uses triangle, half-sine, and parabola curves to simulate the opening and closing process of the boom gun, as shown in Figure 1 .

It can be seen from Figure 1 that the sudden opening of the boom can greatly affect the vibration and stress fluctuations of the boom and cause a certain degree of damage to the structure. Reasonably controlling the opening and closing time of the fire monitor can effectively reduce the vibration of the boom and reduce the stress peak of the boom.

Due to the high working height and high working range of the straight arm lift high fire truck, when the arm is fully extended and the second arm is at the horizontal and the maximum working range is reached, the arm frame is greatly deformed. In particular, when the monitor is operating, the concentrated load causes the boom system to withstand large bending moments. At this time, the boom system is under the most severe conditions. Therefore, when the boom guns fire extinguishing agent, try not to spray the extinguishing agent when the two arms are at the level.

2 . 2 lift high fire truck water supply pressure and flow relationship

In actual use, the working pressure of the boom gun is limited by factors such as the pressure that the fire truck can provide and the back pressure that the boom can withstand. Some of the technical parameters related to the boom gun pressure, flow rate and range of the high-ejection fire truck are shown in Table 1 .

In GB 19156-2003 (gun fire general technical conditions "provides dual guns rated working pressure limit 64 ~ 120 L / s flow rate of segment 1. 2MPa, artillery fire maximum working pressure must not exceed 1. 6 MPa. From Table 1 shows that, for high jet fire in the fire pump maximum lifting height range of the boom, the boom gun water flow is generally in 60-80 L / s, which is substantially the working pressure does not exceed 1. 0 MPa, boom gun The working pressure did not reach the upper limit of the standard, and its reaction force to the boom was within the allowable range.

Fire guns will increase in both flow rate and range as the operating pressure increases. However, as the pressure increases, the flow and range increase will be small, and the load on the jib will increase, that is, the reaction force will increase and the fire extinguishing process will increase. There is some danger in it. Therefore, the fire monitor should increase the pressure and flow of the boom gun within the working pressure range in accordance with the fire control requirements.

2 . 3 lift high fire truck maximum water supply height

The maximum water supply height for a high fire truck refers to the maximum spray height achieved by the fire extinguishing agent. Only the fire extinguishing agent is sprayed to the fire point or the cooling site to meet the fire extinguishing needs.

According to the analysis of the application performance of the JP32 high jet fire sprinkler operation, the water supply pressure is 1 . At 0 MPa , the fire monitor has a range of 35 1TI . From a conservative point of view, the extinguishing agent range for JP20 and JP32 can be selected to be 30 ITI . The fire extinguishing agent range for JP42 , JP56 and JP72 can be 70 m . The elevation angle of a high fire truck cannon is typically -45 . ~ +90 . Based on the analysis of the cantilever water supply form, the maximum water supply height of the lift jet engine with different lifting heights can be obtained by formula (1) , as shown in Table 2 .

By analyzing the data in Table 2, it can be seen that the higher the lifting height of a high fire truck, the more the maximum water supply height is increased. Lifting height of 32 m and below can increase the water supply height by 15 to 30 m . Lifting height above 42 1TI can increase the water supply height by 35 to 65 m . The above data shows that when a high-fire engine is allowed to approach the object of extinguishment in the fire, and the fire can reach its required pressure flow, the 56- and 72-meter high-lift fire truck can spray the extinguishing agent to 90 m. the height of.

3 lifting high fire truck water supply protection

The demand for fire extinguishing agent during the fire extinguishing of petrochemical industry is considerable. Continuous fire extinguishing agent protection is the most important link in the extinguishing process and is also the prerequisite for ensuring that the high-lift fire engine can achieve its maximum combat effectiveness.

3 . 1 water supply method

The flow rate of guns for high fire trucks can generally reach 50~70 L / s . If the flow rate of water guns for each lifting fire truck is 60 L / s , the water consumption per hour can reach 216 tons . Generally, high fire trucks are equipped with water tanks, but the capacity of the water tanks is too small, usually 4 to 7 tons , which is far from meeting the needs of fire fighting and rescue missions. If the supporting vehicle equipment cannot keep up, high-lift fire engines cannot be used. effect. In order to ensure continuous operation of the fire engine, the driver should observe the water level indication of the pump room after the water is discharged from the pump. When the water level drops, the driver should immediately rely on a special fire hydrant, water supply fire truck or remote water supply system to perform the replenishment operation.

(1) Fire hydrant water supply. In petrochemical fires, when fire hydrants are supplied with 65 mm caliber water, it is basically necessary to use two fire hydrants to meet the operational needs of a high-emission fire engine. The number of fire hydrants within a certain range of petrochemical facilities is limited. Before the previous command center arrived at the scene, it was difficult for the participating forces to co-ordinate and coordinate their operations, and a stable water supply line could not be formed. Therefore, the demand for water for high-ejection fire engines could not be guaranteed. Once the water supply is not guaranteed, it will make the high-emission fire engines become furnishings, and it will become an obstacle to the passage of other fire engines.

(2) Water supply for tank fire engines. According to the actual shooting test of the vehicle, when the rated flow rate of the lift jet engine is 60 to 75 L / s , four water supply vehicles are required to carry water. For fires in the petrochemical facilities area, the roads are circular fire lanes, and there are few locations for water supply and fire trucks to choose to stop. Fire fighting vehicles have a small space for operation and it is difficult to use the water transportation method. In this case, a large number of tank fire trucks are required to supply water in series. The method of relay water supply is adopted, but the flow rate of the relay water supply fire truck cannot be less than the shot flow rate of the high fire truck. For example, when a high jet fire sprinkler flow rate of 60 L / s is required, a tank fire truck is required to use 80 mm in fire suppression in the installation area. The water is supplied by the double-stranded water line, and the flow of each main line must not be less than 30 L / s .

It should be noted that the pressure of the water supply vehicle must not be greater than 1 . 2 MPa , when it is necessary to pressurize or decompress the water supply, it should be carried out slowly to prevent water hammer from causing casualties and equipment damage.

(3) Remote water supply system. In most successful cases, under the guidance of a scientific and reasonable method of supplying water to the fire site, uninterrupted water supply to the fire site was ensured, laying the foundation for fighting the fire. Quzhou Gulei fire used a total of three remote water supply systems to ensure the supply of fire water. The remote water supply system is a powerful water supply support for high fire trucks.

Taking a remote water supply system as an example, natural water sources other than 3 000 1TI can be transported to the fire for a long time at a flow rate of 200 500 L / s . In the previous section, the flow rate of firearms used to lift high-powered fire trucks was generally 60~80L / s . Firewater can be selected to have a flow rate of 70 L / s or a flow rate of 50 L / s , and the flow rate of the remote water supply system. to 500 L / s. In this case, the remote water supply system can support 7 water cannons or l0 door foam cannons, that is, it can support 7 to 10 fire fighting vehicles.

Through the above analysis, the following conclusions can be drawn: First, when the water source is within the range of 20 to 200 ITI for high fire trucks , the direct water supply or relay water supply is suitable; second, the distance between the water source and the fire truck is 200 m. In the above, the water supply method combining traditional water supply method and remote water supply system can be used; third , there is sufficient natural water within 3 000 m of the fire field in the petrochemical equipment area , and when there is enough working space, high-power remote water supply can be adopted. The system supplies water, and when the natural water source is more than 3 000 iTI from the fire site , it is necessary to increase the number of booster pumps according to the distance.

3 . 2 water supply time node

The correct water supply method is to ensure the uninterrupted supply of water on the fire site, and the fire extinguishing agent must be provided for lifting the fire truck within an effective time. The operating time of the JP32 lift jet engine is shown in Table 3 .

From Table 3, it can be seen that after the JP32 high-ejection fire truck is parked , it takes 263 S to complete the lift of the boom , that is, about 5 hours. At present, the fire-fighting force equipped with the highest 101 m climbing platform takes 9 rains to lift the fire trucks in place , while the lifted fire trucks have a smaller capacity and rely mainly on external water sources. Therefore, when the fire truck is parked, external water sources must be connected in place within 5 to 10 minutes .

4 Summary

There are three main factors that determine the external fire extinguishing capacity of high fire trucks, namely the actual water supply height, the water supply volume and the water supply security system. Through analysis, the following conclusions can be drawn:

(1) According to the device's ignition and cooling parts, use the high fire truck's own pump system to adjust the boom height, spray angle and distance of fire extinguishing agent, and improve the accuracy of fire extinguishing agent injection.

(2) Within the working pressure range of high fire fighting vehicles, the pressure and flow of the boom guns should be increased according to the needs of the fire field, and the fire extinguishing agent should not be sprayed when the two arms are at the level.

(3) The JP32 type high jet fire fighting vehicle basically satisfies the fire extinguishing needs of ordinary chemical installations when the high fire truck is allowed to approach the ignition device and the fire monitor can reach its required pressure flow . JP56 , JP72 type high jet fire fighting The vehicle can spray fire extinguishing agent to the installation site of 90 m height.

(4) After the high fire truck arrives at the fire site, external water sources must be connected within 5-10 rain . Fire hydrant, water tanker fire truck and remote water supply system can be used for water supply guarantee. Under the condition of natural water supply, the remote water supply system is preferred.

The information in this article comes from the Internet and was reorganized and edited by China Rescue Equipment Network.