In the development of fire protection systems for buildings and structures, special attention is paid to fire protection equipment. The combination of sprinkler and deluge systems provides a reliable barrier to the flame, minimizing property damage. Moreover, from the point of view of protecting people, the efficiency of smoke exhaust fans will be of paramount importance, which reduce the likelihood of suffocation and poisoning by poisonous gas.
The principle of operation of the equipment
Fans of this type cannot be considered outside the general context of fire protection. The task of the smoke removal system as such will be the timely removal of combustion products from the target room (one or more). At a minimum, technical and construction infrastructure should be provided, which in principle provides the ability to move smoke. It is formed by a network of air ducts, at the ends or at the beginning of which ventilation power plants are located. These are mines that have a direct exit from the building. The electrical equipment filling is installed in the cabinet of the smoke exhaust fan, to which a system of sensors for fixing the ignition and an electric motor is supplied. At the time of registration of a signal about the presence of fire or smoke in the room, the control panel automatically instructs the fan to be installed, after which the process of circulation of air flows starts with the removal of harmful gases and other combustion products.
Axial fans
The simplest version of the power plant, providing air circulation. This fan is distinguished by its compact size and high performance, therefore, if the installation is technically feasible, it is initially recommended that this design be chosen. The functional parts of the equipment are the axis of rotation with a cylindrical body and several blades. The most common layout is the “impeller - electric motor”. The advantages of an axial smoke exhaust fan include the possibility of mounting on ceilings and even on a foundation basis if there are duct ducts corresponding to the characteristics.
Radial fans
The best option for complex chimney systems with duct infrastructure. The unit consists of a metal spiral housing, motor and impeller. For installation, a support rigid structure is also provided, on which a fan is mounted. The main advantage of such models can be called functionality. In most cases, the radial smoke exhaust fan allows for the structural possibility of turning the casing. Both when installing the exhaust pipe, and during further operation, the direction of the housing can be adjusted by turning in the right direction at an optimal angle relative to the central ventilation line. The layout inside the structure is usually carried out according to one scheme in which the bearing base of the impeller is mounted directly on the rotor of the engine.
Location classification
Fans for smoke exhaust systems are mounted both indoors and outdoors. The most common are wall structures, which are often installed in technical rooms. Outside, smoke exhaust fans are usually used, which are characterized by high performance with support for discharge pressures up to 1500-1800 Pa. Moreover, on the roof, thanks to the free space, the installation of entire fan complexes, which are formed from several units, is practiced. Smoke emission can be directed in different directions or straight up.
Equipment management
Workflow control is provided through the above-mentioned electrical cabinet. As a rule, such panels provide switching circuits for 220 V with a maximum voltage of up to 400 V. Directly control the smoke exhaust fan is carried out manually, automatically or remotely. In the simplest configurations, the operator, at the time of detecting signs of fire, puts the unit into operation via the cabinet switch.
The automatic control method involves connecting fire and smoke sensors that transmit the corresponding signal to the control panel of the cabinet, after which the fan is activated regardless of the operator's actions.
In the remote operation mode, the responsible person can start the operation of the equipment using a special remote control or a radio tag at a distance. For automatic and remote control, preliminary adjustment of the equipment with programming of algorithms for its operation is required.
Areas of application for smoke exhaust fans
There are various configurations of equipment that make it possible to operate it in both domestic and industrial facilities. For example, many manufacturers produce small-sized installations designed specifically for home supply and exhaust systems. The user only needs to mount the compact fan into the shaft and connect it to the network.
As for the industrial sector, large facilities are provided with local smoke exhaust fans to maintain fire safety in workrooms, in welding areas, in spray booths, etc. High-performance hoods serving multi-meter duct networks are used in public buildings. General exchange fans, for example, are used in schools, restaurants, libraries, office buildings, etc.
Nuances of choosing a fan
In addition to the design features, dimensions and control system, it is important to consider performance. These include engine power, operational properties of materials, the possibility of contact with aggressive air mixtures, etc. As for the power potential of an electric motor, it averages 500-3000 watts. Both household and industrial units with a rotational speed of the blades of the order of 900-1200 rpm are represented in this range. By the way, the price of a smoke exhaust fan, on average varying from 7 to 15 thousand rubles, will largely depend on productivity.
It is equally important to calculate the possible loads under which the unit will work. This primarily relates to temperature. The average fan for a smoke exhaust system withstands about 400-600 ° C. But also takes into account the concentration of harmful materials, explosive gas mixtures, dust and aggressive fumes. The class of protection IP54 is considered optimal, which allows the content of impurities in the working environment to 100 mg / m.
Conclusion
The basic design of the fan systems in question may seem outdated and impractical to use. Especially against the background of the advent of ever new multifunctional and compact fire protection systems. But is there an equivalent alternative to smoke exhaust fans precisely from the point of view of minimizing the harm from combustion products? The only alternative is a static ventilation system, which does not involve the removal of smoke at all. On the contrary, such equipment blocks the burning in one room, stopping the supply of oxygen as a flame stimulator. The choice of a particular system should be selected based on operating conditions, target characteristics of the premises, etc.