How do you know a few ways to fire water?

01. Preface

In some previous articles, we discussed direct attacks. Simply put, the direct attack is to spray water onto the burning material. The purpose of doing so is to reduce the surface temperature of the combustion material.

All solid combustibles will begin to produce a pyrolysis gas at a specific temperature that will sustain the combustion of the flame. If the temperature of the combustion surface drops below this critical temperature, the pyrolysis will stop and the fire will extinguish.

This particular firefighting tactic can be applied in many different ways. The situation faced by firefighters will determine the best way to use direct attack.

02,

Spot shots were introduced to Belgium in the second half of 2000 and were taught by a Frenchman named Pierre - Louis Lamballe in the Walloon region. They were quickly promoted in other parts of the country. Since 2010 , it has become part of the firefighter training course.

The meaning of the burst fire is to allow the firefighters to find a fire point and extinguish the fire during the attack. While advancing towards the fire point, firefighters will continue to cool the high-temperature smoke in the smoke, and once they find a fire point, they use the point fire to start a direct attack.

Spotting is just a direct attack, using less water. Set the squirt gun to spray DC water, then slowly turn on the water gun and wait for the water to come into contact with the fire and turn off the squirt.

It must be noted that the water gun must be opened slowly. Everyone often makes such mistakes by quickly opening the water gun. This will cause the water to have a strong impact on the fire. This must be avoided.

Another reason that the water gun needs to be opened slowly is that this is related to the size of the water droplets. When the water gun is slowly opened, relatively large, thick water droplets form.

In the direct attack, the size of the water droplets is very important. Water droplets are too small and water droplets will not reach the point of the fire.

To do this, we need large, thick drops of water because they will fall to the surface of the burning material and evaporate. Ideally, water will slowly flow down the combustor, which will cool the combustor surface as much as possible.

The size of the water droplet is different from the size of the water droplet required to cool the flue gas. When cooling the flue gas, the water gun needs to be opened as soon as possible. The flow rate of water is large and the water droplets produced are smaller, because the water is flowing through the rod at the front end of the water gun. Conversely, when the water gun opens slowly, the flow rate is lower, and the resulting water droplets will be thicker.

Figure 1 Two different nozzles.

The left nozzle is equipped with a rotating gear ring, the water flow will make the ring rotate, resulting in smaller droplets; the structure of the right nozzle is completely different, this nozzle uses the fixed teeth on the cone device, it will form a small droplet . (Shooting: German Berckmans )

The shot is to repeat this action (slowly open the water gun, wait until the water touches the fire, then turn off the water gun) until the fire is extinguished. This technique is ideal for extinguishing a small area of ​​fire because it uses very little water.

Especially in an inadequately ventilated fire, when firefighters face a small range of ignition points in a low visibility environment, any excess steam generated by the water gun will cause further reduction in visibility. In this case, using bursts will be a good choice.

In the past, spot shots were always used in combination with cooling flue gas (the operation method is almost the same, the shots need large drops, the water guns need slow opening and slow closing, the cooling gas needs small drops, and the water gun needs to be opened and closed quickly), resulting in “ "Pulse Injection" technology - Spotting is a technique suitable for small fires. Because of its discontinuity, the cooling capacity is quite limited. It takes a while to control the fire.

During this time, firefighters also need to control the smoke layer above them, and the best way to achieve control is to cool the smoke.

03,

Shots and shots were introduced in the same way. It was the next step in Pulse Shot. The fire extinguishing unit has already controlled the current fire and started to advance toward the fire point, starting the final fire extinguishing and cleaning up the remaining fire.

The squirt was still set to spray DC water, but the nozzle was only slightly open to shoot only about 1 meter of direct water. Due to the very low flow rate, the formation of thick water droplets will further reduce the temperature of the combustibles.

Australian fire officer John MacDonald thought of another method of using fire, he used strafing instead of shooting. Assume that the firefighters start the internal attack during the development phase of the indoor fire. During the advancement toward the fire point, the firefighters will cool the smoke, and the long “pulse shot” has a positive effect on the continuous control of the smoke layer above. Imagine that the firefighters met a large sofa on the offensive, and most of them were on fire, and the shots were no longer suitable for use. The cooling power of the burst shot is too small for this kind of fire. In addition, such fires are often close to flashing and must be quickly extinguished.

In this case, the fire can solve the problem. The water gun slowly opened again and the water flow was set so that the water just reached the sofa in a small arc, so that thick water droplets would form again. Instead of shutting off the squirt gun, the squirt gunner opened the squirt gun and shook the water to spray the water onto the entire surface of the sofa, continuing the action until the fire was extinguished.

04,

The term "full jet" is used to describe the shape of the water stream. In Belgium, it is also used to define a method for using the entire flow of water guns. When the squirt gun is fully open, the water stream will shoot out quickly, so it doesn't matter if the squirt gun opens quickly or slowly. After a few seconds, the water reaches its maximum flow rate. This method is applicable to several different situations and can also be classified as "direct attack."

4.1. Large fire

Assume that firefighters arrive at the scene and find that burning is a large wood stack. The rate of heat release from such a fire can easily become very high.

Preventing the spread of flames to other unburned areas will be one of the main focuses of the fire fighting operation. If there is only a pile of about 10 wood piles, the blasting technique will be a good way to deal with this kind of fire, and the radiant heat will be controlled. Once the direct attack begins, the fire will quickly decrease.

However, when there are many stacks of wood that are closely connected, the radiant heat will be greater. It is impossible for firefighters to get close enough to spray arc water to extinguish a fire. In addition, such fires require higher cooling capacity than the blasting technique.

In this case, it is recommended to fully open the water gun, which can bring greater control range and greater flow. For large fires, this type of direct attack is used.

Even if the cannon's flow exceeds 4,000 liters per minute , it can spray water onto the wood stack for direct attack.

Figure 2 Direct Attack Using Water Guns

4.2.

Assume that you are about to enter a naturally ventilated fire, and that the fire has already been in full combustion. If you can reach the vent, the fire can be extinguished using an indirect attack.

However, this is often the case: When using fog water to indirectly attack these vents, the water cannot reach the vents. For example, the flame is running out of the window on the third floor. In this case, you can use "full jet" for direct attacks.

It is impossible for water to be sprayed from the ground to a burning object. The only way to do this is to take a boarding car. However, it takes some time to deploy and provide water for it.

It is achievable to shoot water from the ground to the ceiling of the third floor. This can be achieved quickly by connecting a hose line with a diameter of 45 mm or 70 mm directly to the pump of the fire truck and start an external attack.

High-pressure booster lines are not recommended because high-pressure hose reels have limited flow (the higher the pressure, the lower the flow rate) is probably not enough to extinguish the fire. Finally, the high-pressure hose reel will continue to be sprayed for a longer period of time. It means that more water will be used during the extinguishing process.

The water that hits the ceiling will splatter and fall, so that some of the water will fall on the combustion in the room. Of course, this is not as effective as directly injecting water into the combustion, but it is still an effective method. Since the purpose is to reduce the temperature of the fire load, this method is also classified as a direct attack.

This offensive is part of a "transitional offense" tactic. In this tactic, first use a full jet for external attacks.

It is worth noting that this is only for a short period of time and the entire jet only needs to last for about 5 to 15 seconds. Its purpose is to reduce the fire. The second part of the transitional attack is made up of classic introjections. Its purpose is to prevent external jets of water for more than 30 minutes.

Maybe we can agree on this issue in the fire-fighting operation - if a fire is in the full-firing stage on the floor above the ground floor, and when the full water flow can reach the opening from the ground, then using the full water flow to attack it is to solve it. This is the best way to fire, and this should be part of the standard procedure for dealing with such fires.

For fires located on floors 1 to 4 , a 45 mm hose can be connected directly to the pump of the fire truck using a different-diameter interface . If the fire occurs on the 5th to 7th floors, a 70mm diameter hose is required . The 70mm hose has a higher water supply. Of course, the 70mm diameter hose can also be used for the first 4 floors. The disadvantage is that it requires more people. Laying hose.

If a 70mm diameter hose is used to extinguish the fire on the 6th floor, the reaction force of the water gun will be very large and several firefighters will need to hold the water gun and hose.

This means that firefighters will not be able to deploy internal waterfloods until the fire is extinguished. If a 45mm hose is used , a two- person team can lay the hose, and another two- man team can perform an external attack, which will result in faster and more effective firefield operations.

For 8 or less than 8 layers of fire, the monitor can be installed in the vehicle is ascending fighting, of course, compared with the laying of water from the ground, it will take longer.

On the other hand, the internal attack team also takes a long time to advance to the floor below the floor of the fire, and initiates internal attacks from there. At this time, the coordination between the internal attack and the two groups of the ladder truck becomes even more important.

4.3.

Imagine a fire broke out in an apartment when it reached the fire. This is a large building with a fire tongue that blew out from the back of the building.

Due to the size of the building or the limited access to the surrounding area, it is not possible to launch external attacks. For example, a window that spurts fire is located directly above the floor where the parking lot is located (the first floor we often say).

The solution is to launch a classic internal attack. The attack group will attack from the stairwell. As soon as they opened the apartment door, smoke would flow into the stairwell and the firefighters would continue to cool the smoke as they advanced.

If the fire in the living room is in an all-burning stage, the temperature of the flue gas flowing into the hallway leading to the living room (the hallway connected to the living room) will be very high, and flue-gas may also occur in the smoke layer of the corridor. Offensive players need to actively cool the smoke layer, and by using long “pulse shots” they will be able to move along the hall.

However, it is possible that firefighters will have to stop at some point because it is too hot. At this time, they may not have reached the point where indirect attacks can be implemented. Indirect attacks are an ideal way to control the fire.

There is another way to shoot the entire jet through the door to the ceiling. A portion of the water will bounce off and fall onto the burning material, which may reduce the heat release rate of the fire. The outward flow of hot flue gas will be reduced so that the internal attack team can move forward again.

Again, this is a form of direct attack that can be used if circumstances require it. In addition, when using a high-pressure hose reel, this type of direct attack is likely to fail (small pressure high flow).

05,

This article extensively describes the different ways in which direct attacks can be carried out during firefighting operations.

Some technology uses very little water (penciling burst), and some techniques used water a little more (painting fire), some technology will use a lot of water (full jet Full jet), by firemen in the fire Select the appropriate technology to implement the fire extinguishing action.

As an organization, the fire department has a responsibility to let firefighters know in a clear way what actions they should take.

In the process of fire suppression, different fire extinguishing technologies can be directly transformed according to the environment of the fire site. In addition, different technologies can be used simultaneously or sequentially. This article can be summarized as the following:

"How much water? As much as needed!"

"How much water is needed for fire extinguishing? The more, the better!"

This article is reproduced from WeChat public number: Orange Rescue.