Air backing system. Just about complicated.

What is the air support? From the official term: increase of air pressure above atmospheric before the barrier, etc. Reduces the jaw. In any case, I did not immediately understand. I had to understand. In a certain place, usually on the stairs, a fan is installed, which, when the alarm is triggered, starts to catch up with the air from the street (increase the pressure). The fans of air supply are usually very powerful and can operate without power limitations in the entire range of performance. In fact, this is the whole system of air supply. Its task is to ensure that in some zones, which are evacuation routes, the air pressure is greater than in other rooms. Thanks to this, the smoke air will not penetrate into these zones and will not prevent people from moving to a safe place or leaving the building that burned.
The calculation of the air supply is carried out according to the worst scenario. The fire will occur at a strong wind speed, with destroyed windows and open doors and lift shafts.
When installing the supply air fan, take into account:

• Location (the uppermost level of the room or staircase);
• The excess pressure on evacuation routes must not exceed 150 Pa (in order not to impede the opening of doors);
• The minimum pressure must not be less than 20 Pa;
• Hydraulic resistance;
• The air intake point is located on the windward side of the building.

People who never encounter fire-fighting measures for the most part are unaware of smoke removal systems and air suppression. And meanwhile, most people die during the fire precisely from choking and poisoning with carbon monoxide. Smoke instantly spreads and penetrates into the most remote corners of the building. Remember, if something burned on the stove, the stench is felt throughout the apartment. Similarly, with carbon monoxide! It penetrates everywhere with great speed, but unlike the unpleasant smell. Carbon monoxide is dangerous. When its concentration exceeds the norm, you are not able to adequately reflect and navigate in space. You can not find a way out of the smoke-filled premises and evacuate. To avoid the catastrophic consequences of smoke and poisoning, smoke removal systems are created.

In accordance with the rules of SP 7.13130.2013 and Regulation FZ-123 smoke exhaust systems are equipped with:

• Corridors;
• Halls;
• Staircases ;
• Basements;
• 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. The smoke removal system removes smoke and carbon monoxide from the premises, increasing the likelihood of people's survival. Therefore, the functionality of the smoke and air conditioning system is different. And most importantly, completely different technical features. Smoke removal systems are more powerful. Before them is the task to remove all the polluted air from the premises in the shortest possible time. Calculations are made in accordance with clause 7 of SP 7.13130.2013. In addition to removing combustion products, the smoke removal 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 forbidden by regulations), so the division is arbitrary and is not worth a detailed examination.

The smoke-free ventilation consists of:

• Fan;
• Air duct;
• Smoke exhaust valves;
• Air back - up system.