Smoke extraction hoods: types, functions, installation

The ignition, as well as the subsequent spread in the smoke room, leads not only to large financial losses, but also to death of people. Most of us believe that in case of fire the main danger comes from exposure to high temperatures, but sad statistics prove that exposure to harmful substances and combustion products is no less dangerous to health.

Operating principle

The system of natural smoke removal is based on the principle of air heat flow. It has several ways to control the mechanisms: remote control of smoke flashes via infrared rays, control panels and special sensors, as well as manual buttons.

Ventilation systems of natural motivation can be used in all types of rooms, you only need to select the necessary scheme. SNiP (sanitary norms and regulations) determine all necessary fire resistance indicators for each type of premises.

Depending on the purpose of the enterprise and its patency, various combinations of the system can be installed: separate windows with electronic control for enterprises with a small number of people or special complex systems that meet more serious fire safety requirements.

Design and calculation of smoke flues

The design of smoke removal systems is carried out in several stages.

First of all, it is necessary to study all the technical documentation for the installation site.

The next stage involves the examination of existing ventilation shafts (if any) and their detailed analysis. And only after that you can proceed directly to the calculations.

Inspection of the design object is a very important stage, since only after it can you find the equipment that is most suitable for the given room. In the absence of ventilation shafts at the facility, specialists determine whether there is the possibility of additional communications. If there is such a possibility, you can start the calculation.

Functions of smoke hatches

Hatches are designed to be used to:

1. Natural uniform lighting. As you know, the top lighting is twice as effective as the side lighting. Since the smoke flaps cover almost every square meter of the room, the cost of lighting is very significant. In addition, natural daylight increases efficiency and improves well-being, which is very important in office buildings.
2. Natural ventilation. Constant circulation of fresh air ensures the maintenance of a comfortable temperature in the room, which again allows to save considerably the costs of artificial ventilation.
3. Smoke removal. Smoke extraction in an emergency situation ensures effective use of evacuation routes and effective operation of rescue services.
4. Significant simplification of engineering systems. Hatches smoke in certain cases are able to eliminate the need for artificial air vent.

Smoke control systems

The management of smoke flue hatches is carried out with the help of specialized systems of three types: a ventilation control system, a smoke control system and a mixed system.

Also, the systems are subdivided according to the type of control of the mechanism. They can be of three types: pneumatic, electric and pneumatic-electric.

Smoke removal hoods activate the control system automatically with the help of special sensors that react to rising air temperature or smoke in the room. However, at the customer's request, the smoke removal system can be additionally equipped with remote and manual start-up devices, as well as triggering through a fire alarm system.

In addition, the ventilation hatch management system can be equipped with special sensors and a weather station. In this case, in case of strong wind and precipitation, the hatches will be closed automatically.

Practical recommendations for installing smoke flaps

The main condition, in which the installation of smoke flue hatches can be considered correct, is their uniform arrangement on the roof of the building. However, if materials of different combustion intensity are located in the room, uneven placement of hatches is allowed.

When installing hatches, account should be taken of the angle of the roof: if it is less than 12 degrees, the maximum distance from the roof edge to the hatches is 10 meters, if it is more than 12 meters, the distance increases to 20 meters.

The distance between hatches should be at least 20 meters and not less than the sum of the long sides of the two hatches (or their diagonals).

From the practical point of view, a large number of small hatches, rather than a small number of large hatches, will be much more effective with their task. A roof slope of less than 12 degrees implies the mandatory installation of at least one hatch of 200 square meters. M, more than 12 degrees - by 400 square meters. M.

Hatches smoke can be installed on roofs with different types of coating: membrane, reinforced concrete, etc. It is mandatory to take into account the layout and load calculated at the design stage. The most frequent consequence of errors at this stage is the overcooling of the room in winter and overheating during the hot season.

Special requirements

When determining the number of smoke flue hatches in places of mass congestion, their area should equal or be more than 3% of the floor area of this room.

The methodology for calculating the area of the smoke escape hatch is as follows: if the floor area of the stage is less than 150 square meters. M, the smoke flue must be at least 3% of it. If the surface area of the scene exceeds 150 square meters. M, the area of the smoke flue hatches is calculated by the formula: A = 0.5 √2F-100 (F is the surface area of the floor of the stage).

Thus, the article details the types of smoke flue hatches and the issues of their installation.