What is air pressure? From the official term: increase in air pressure above atmospheric pressure in front of an obstacle, etc. reduces the jaw. In any case, I did not immediately understand. I had to understand. In a certain place, usually on stairs, a fan is installed, which, when an alarm is triggered, begins to draw air from the street (increase pressure). The air inlet fans are usually very powerful and can operate without power limitations in the entire performance range. In fact, this is the entire air supply system. Its task is to ensure that in certain areas that are escape routes, the air pressure is greater than in other rooms. Due to this, the smoky air does not penetrate into these areas and does not prevent people from moving to a safe place or leaving an illuminated building.
The calculation of air pressure is carried out according to the worst-case scenario. A fire will occur at strong wind speeds, with broken windows and open doors and elevator shafts.
When installing the air inlet fan, the following is taken into account:
- location (the highest level of the room or staircase);
- excess pressure on the escape routes should not exceed 150 Pa (so as not to interfere with the opening of doors);
- while the minimum pressure should not be less than 20 Pa;
- hydraulic resistance;
- the air intake is located on the windward side of the building.
For the most part, people who are never confronted with fire-fighting measures are unaware of smoke exhaust systems and air intake. Meanwhile, most people die during a fire precisely from suffocation and carbon monoxide poisoning. Smoke instantly spreads and enters the most remote corners of the building. Remember, if something is burnt on the stove, the stink is felt throughout the apartment. Similarly with carbon monoxide! It penetrates everywhere with great speed, but unlike an unpleasant smell. Carbon monoxide is dangerous. When its concentration exceeds the norm, you are not able to adequately reflect and navigate in space. You cannot find a way out of a smoky room and evacuate. To avoid the catastrophic effects of smoke and poisoning, smoke removal systems are created.
In accordance with the rules of SP 7.13130.2013 and the regulations of FZ-123, smoke exhaust systems are equipped with:
- corridors;
- halls;
- stairwells;
- basement facilities;
- tunnels
In all dangerous places without natural light.
When a fire alarm is triggered, normal ventilation is blocked because it contributes to the development of a fire. A smoke exhaust system removes smoke and carbon monoxide from rooms, increasing the likelihood of people surviving. Therefore, the functionality of the smoke exhaust system and air conditioning is different. And most importantly, completely different technical features. Smoke exhaust systems are more powerful. They are faced with the task of removing all polluted air from the premises in the shortest possible time. Calculations are made in accordance with paragraph 7 of SP 7.13130.2013. In addition to removing combustion products, the smoke exhaust system removes excess heat. Prevents the spread of smoke and carbon monoxide between rooms (fire zones). It is aimed at cleaning the evacuation routes, as well as the directions of the fire brigades. Thus, the smoke exhaust system is divided into supply and exhaust. They are always used together (separate use is prohibited by the regulation), therefore division is conditional and not worth a detailed consideration.
Smoke ventilation consists of:
- a fan;
- air duct;
- smoke exhaust valves;
- air pressure system.