Introduction of positive pressure smoke exhauster

Few fire fighting equipment will be as cheap as PPV smoke exhausting equipment. It can quickly and effectively extinguish fire, increase the survival rate of trapped people, and help fire extinguishing inside buildings. How to properly use PPV smoke evacuators and quickly control the fire to save more lives is a required course for firefighters.

Smog danger

The flames rushing out of the window of the building immediately attract the attention of the firefighters, but they seem to feel less dangerous. It's just that we have to be clear that the danger is not only caused by fire or heat radiation. In fact, smoke (burning gas) may also become a dangerous enemy. Smoke can quickly spread to entire buildings. It is so deadly, yet silent, that it can spread the danger quickly from the source.

toxicity

A lot of dangerous ingredients can be found in the smoke. Carbon monoxide is just one of them, probably accounting for 1% of smoke , but only 1200ppm (about 0.12% ) poses a threat to life and health.

Not only that, the toxicity of smoke can also pose a threat to the lives of firefighters. Therefore, the rapid removal of smoke from the interior of a building will not only increase the duration of the trapped but also increase the safety of firefighters.

Visibility

As the fire develops, the oxygen in the enclosed space will be consumed, and smoke will gradually diffuse into the air. Another point is that it is impossible for the fire to continue to burn in the absence of oxygen. The speed of heat transmission will be limited by the vents, and the fire will be controlled by the air flow.

The flow of air to control the fire will also produce a large amount of incomplete combustion, the vast majority become soot. The drop in visibility in the air directly leads firefighters to lose their most useful senses—the perspective. Decreased hearing and touch also increase the risk. Removing smoke can regain sight and allow firefighters to quickly find the location of the fire.

Combustibles

Smoke contains a large amount of incomplete combustion and gases produced by the combustion of fuel (pyrolysis). Smoke contains a combustible substance that can easily reach the ignition point with only a little air (oxygen) heating. Therefore, the spread of smoke means that the fire may spread because the two conditions of fuel and air are easy to do.

When smoke is present in buildings, insulating large amounts of combustibles will greatly reduce the risk of fire spreading.

temperature

The isolated smoke above the flame can easily reach over 500 degrees, with the development of the fire. The smoke produced by combustion can generate a lot of heat radiation. The surface of the combustible material was not affected too much by the pyrolysis fumes at the initial stage of combustion. However, thermal radiation poses a threat to trapped people and firefighters entering the building. This will also make fire rescue very difficult and even helpless.

Cooling the heat in the flame will not only increase the duration of the trapped person, but will also allow firefighters to find the source of the fire more quickly.

Using ventilation technology must have a certain strategy

Currently, the most cutting-edge fire fighting strategy is to regard ventilation technology as an important fire-fighting technology. The key is to grasp the time and coordinate the interaction between fire fighting water, fire extinguishing and ventilation technology inside the building. A recent study by the Underwriters Laboratories showed that modern furniture equipment is easier to ignite than before, the time required to be ignited is reduced by a factor of four, and the peak temperature is very high. The flame reacts strongly to air circulation. Once the quickly extinguished flame meets fresh air, the fire will increase rapidly in a very short time. Firefighters need to quickly find the flame and extinguish it in this very short time.

Compared with the traditional flammable furniture, the peak temperature is very high, and the time passes quickly. Therefore, it is necessary to quickly find the real burning flame in a short period of time.

Therefore, we must emphasize that the coordination of fire water and air circulation is determined by the rapid reaction of fire and air circulation. Air circulation may improve the internal fire extinguishing environment of the building, but if the fire water is delayed, the increase in fire will make the fire extinguishing environment worse.

Natural ventilation mainly depends on the fire to discharge the smoke. The flow of air and smoke is mainly due to the pressure difference: the flow mainly spreads from high pressure to low pressure along the path of least resistance.

However, due to the very small pressure difference generated by the flame, the ventilation effect is not good and takes a long time. When the room is on fire, the natural ventilation method does not improve the internal fire extinguishing environment, and the flame reacts to the air flow and generates more smoke.

However, PPV smoke extractors can use a ventilator to create a pressure difference in the building by increasing the original pressure difference created by the flame. This is to find an effective and lasting ability to eliminate smoke for the ever-increasing fire protection requirements.

Advantages of using PPV smoke exhauster

Increase visibility

Increasing visibility means increasing the speed of internal fire extinguishing. Fire-fighting water can be found faster, escape exits can be found faster, and search and rescue can be faster if there is a distress signal.

Increase the persistence of trapped people

When the PPV fume hood starts to be used, it will provide a layer of breathable fresh air to the trapped people lying on the ground. PPV smoke machines can help many trapped people in a very short time.

Reduce the temperature

Fresh air instead of hot air inside will greatly reduce the internal temperature.

Reduce the total amount of combustibles

In buildings where there is a fire, there must be a lot of combustibles: incomplete combustion products and combustible gases from the pyrolysis of combustibles. The use of PPV ventilation means that combustibles are blown out of the building and no longer increase the rate of flame heat release, thereby reducing the chance of a crash.

In a dense smoke-filled enclosed environment, it is usually an unclear, high-temperature, smoke-rich and toxic operating environment. It is very difficult to extinguish fires in depth.

The use of PPV smoke exhausters for fire extinguishing is a significant improvement of the internal fire extinguishing environment. Extinguishing water can quickly reach fire extinguishing points to avoid the spread of fire. In summary, the use of PPV smoke exhauster is in response to the needs of a more complex fire extinguishing environment.

Defensive PPV : Isolating Flame Keeps Dangers From Trapped Persons

In a multi-family building, the most dangerous area is where smoke is enveloped. The most important areas of concern for the smoke are the corridors or stairwells, which are used as public exits for households. Smoke in those places is cooler than the smoke in the enclosed space, which makes natural ventilation difficult to play. Isolating the room where the fire occurred, using the PPV method to quickly clear the smoke out of the room where the fire occurred, is a very common strategy in Europe, also known as "defensive PPV ." This method can not only ensure the smooth exit of the residents in the building, but also ensure the smooth progress of search and rescue operations in the safe area during a fire.

The classic defensive PPV is in a high-rise building. The fire area was separated and the PPV was able to quickly clear the smoke from the stairwell to ensure that residents in the building had a safe escape route.

PPV can create a one-way flow channel

When a PPV ventilator is placed at the entrance gate, all the windows can be seen at the exhaust port. The “smoke exhaust” can discharge the smoke from the place where the flame occurs. This is called the solitary stream. Firefighters can safely and flexibly enter the building along the wind direction of the ventilator. If you do not use PPV , you only know one bidirectional flow channel. Smoke drifts from above the building and air enters the building from below. Bi-directional flow conditions make it easier for firefighters to be exposed to flame smoke and the fire extinguishing environment becomes worse.

The United States RAMFAN gasoline-driven positive pressure fan, also known as mobile smoke machine, mobile fan, motor fan, petrol fan, gasoline driven fan, fire fan and fire smoke exhauster. The RAMFAN fan in the United States is the most reliable and best-selling fire-fighting fan in the world.

Advantage:

Withstand the severe test of the first line of fire;

The wind volume of the same kind of product is the largest;

Apply to different environments and conditions.

Precautions for use

No matter which tools, technologies or strategies are used, there is no risk. When using a gasoline-powered PPV hood , consider some other factors:

Fire growth

Ventilation will inevitably bring air, and the air will cause the fire to grow. Due to the use of modern homes, the flame produced by combustion reacts more violently to venting and exhausting. This has already been explained previously. When PPV is used to make air flow passages (aggressive PPV or "positive pressure"), fire extinguishing water must be followed as soon as possible to control the fire growth. But if the flames are separated, the PPV ventilators are not facing the flame ventilation (defensive PPV ), the flames do not get more air, and the fire will not grow.

The spread of fire

In many cases, blowing smoke out of a building will blow flammable gas into areas where there is no fire, and this will cause the fire to spread. When the direction of air flow is not properly manufactured by PPV , the smoke is blown into a small space or other space, which can also cause the fire to spread. Therefore, when using PPV , it is necessary to fully and thoroughly evaluate the fire scene.

PPV use needs coordination and training

Fires are dynamic and PPVs can quickly change the conditions under which fires occur. It is very necessary for the coordination and timing of ventilation and firefighting. Comprehensive training is very necessary for PPV 's various usage strategies. Only by strengthening the training can the correct and flexible use of PPV 's fire fighting strategy be based on different fire scenes .