A fire damper for ventilation is a special device through which it is possible to exclude the possibility of combustion products entering the system. Thanks to them, living and working rooms are completely cut off from the source of ignition. They are made of heat-resistant and fire-retardant materials and remain functional under prolonged exposure to high temperatures. The installation and maintenance of these elements is organized and implemented in accordance with the norms in force in building practice.
Features of fire blockers for ventilation
For modern communication systems, on which the safety of people in case of fire depends, strict adherence to the requirements of current standards is mandatory. All of them are aimed at protecting the operating ventilation from gaseous and solid combustion products. In accordance with regulatory documents, a fire damper for ventilation systems blocks the channels of combustion products entering the rooms and allows them to be removed from the danger zone.
Principle of operation and scope
The ventilation fire damper works on the principle of most blocking elements, which are normally open. When a fire signal is received, they are transferred to the opposite state ("Closed") by means of the drive mechanism. The various models of these devices differ in their design and the type of drive used.
Valves for blocking smoke and other combustion products are widely used in various facilities, including residential and public buildings. Within typical buildings, they are installed in the following locations:
- walk-through vestibules;
- corridor spans of buildings;
- elevator shafts and similar premises.
The devices are installed at the intersection of pipelines for smoke extraction with ceilings between floors, as well as with walls and partitions of buildings.
Classification of fire-fighting devices
In accordance with the design features and the order of operation, fire valves for ventilation are divided into several types:
- normally closed or NC;
- normally open (NO);
- double acting;
- designed to remove smoke formations.
In the first samples, in the normal state, the blocking valve is closed, so that air does not enter the outlet duct. In the event of a fire and an alarm is triggered, the valve opens, after which, due to natural or forced air flow, smoke is removed through it. In NO devices, in normal mode, the valve is open and air moves freely through the ventilation system. After the fire alarm is triggered, the valve closes, excluding the possible ingress of smoke into adjacent rooms. The most famous examples of such mechanisms include a fire damper of the "KLOP-1" type.
Double-acting products combine the capabilities of the two considered options. They are triggered to close at the start of a fire, blocking the passage of smoke into the adjacent room, and automatically open at the end of the fire.Smoke valves are special devices designed to remove combustion products and are elements of shut-off and control equipment. This type of device is installed in the places prescribed by the current regulations.
According to the method of placement within the ventilation system, the valves are divided into wall and duct. The former are mounted directly on the surfaces of structures without being connected to the existing system, while the latter are placed directly in the air ducts.
Damper types
To control the position of the dampers of ventilation units, special mechanisms are used, called servo drives. In order for such a device to work, an electrical signal is supplied to it from the control module. Several modifications of service drives are known, each of which is connected individually and needs separate consideration.
Drive types
As a rule, fire dampers are equipped with two types of control elements for their state:
- Combined electromagnetic operating mechanism, normally closed.
- Electric actuator, de-energized in the initial position and therefore keeping the valve closed.
A fire-prevention valve for ventilation with an electric drive of the combined type operates as follows. When a fire is detected, a pulse is sent from the sensitive sensors to the electromagnet, under the action of which the blocking voltage is removed from the valve. Its cover is displaced due to the elasticity of the spring in the mechanism. In the opposite state, corresponding to the blocked mode, the damper is manually returned.
The electric drive is also triggered by the pulse coming from the sensor, after which the electric power is supplied to its terminals and the damper opens. It returns to the initial (normally closed) position automatically by a command from the control panel or from the fire extinguishing system. On normally closed fire dampers, their manufacturers install reversible electric actuators of the BE, BLE, BEN and BEE versions. They are designed specifically for critical environments.
In some models of electric actuators, the shutter movement from the initial state "Closed" to the operating state "Open" and vice versa occurs due to the connection of power to the windings. The control signal for closing the valve is here the voltage supplied to the corresponding terminals of the device.
In legacy systems, there are fire dampers equipped with a fusible link and a typical spring return. The use of such drives is prohibited in accordance with current regulations.
Features of the installation of the valve mechanism
For all types of systems, the ventilation fire dampers are positioned to block backdraft from any combination of fans and extractors available. When only one intake point is provided in the ventilation, 1 valve is installed within the duct to exclude reverse draft. With a more complex organization of the exhaust system (in the case of several working elements), the following requirements must be met:
- Each separate branch of the air duct will need to install its own check valve, which will exclude the possibility of reversible air movement towards the switched off hood. Often they are supplemented with another sample mounted at the outlet of the ventilation system.
- The check valve is installed in areas to which access is not limited by anything.
For domestic needs, both round and rectangular air ducts of standard cross-section are optimal. For them, ready-made solutions have been developed, providing for an arbitrary choice of a place for a non-return valve.The procedure for installing it in this case is no different from connecting any typical ventilation element similar to it.
One practical solution for exhaust systems based on plastic ducts or pipes is to place the valve mechanism in the duct connector. If it is necessary to work together two types of systems (natural and forced), the following standard solutions are used:
- installation of a tee next to the ventilation grill, followed by installation of the valve mechanism to the natural ventilation outlet;
- use of gratings of a special design with outlets for each of the systems.
For their fastening, experts recommend using liquid nails or ordinary screws. The first of the above options is preferable, since in this case it is more convenient to disassemble the system in order to overhaul, repair or change the circuit. To do this, simply remove the safety guard.
If you choose the option of installing the valve from the inside of the grill, you will need to carefully seal the joints between it and the channel walls.
