Air control devices are used in ventilation to control air flow or to set up equipment. This category includes plastic air valves for apartment ventilation, and giant heated and electric mechanisms for industry. The effectiveness of air ventilation depends on the correct selection and placement of control devices.
Purpose of air control devices
Air dampers and valves for ventilation are used for:
- air flow control;
- overlapping ventilation ducts during system shutdown;
- debugging work;
- debugging air flow in ventilation ducts.
Air valves are required to stop the movement of air through the ventilation ducts during system shutdown. Modifications of air valves for ventilation with adjustable stops (throttle valves) that change the air flow have been developed. Throttle valves of a standard type are installed in air ventilation systems with a pressure of not more than 1500 Pa and a concentration of solids up to 100 mg per cubic meter.
It is advisable to install air valves in systems with an air temperature not exceeding 800 degrees Celsius and an aggressiveness of the environment, comparable with the quality of atmospheric air. In regions with a cold climate, electrically heated models have been developed for ventilation of air compressor rooms.
Air dampers for ventilation regulate the amount of air supplied in ventilation systems.
Types of ventilation valves and dampers
The main types of air control devices are air valves and dampers. Not a single ventilation system, whether it be an air compressor, an office building or an entertainment complex, can do without these mechanisms.
In form and function, ventilation air valves are:
- round;
- rectangular;
- reverse;
- fire fighting;
- smoke removal.
Round valves for ventilation
They are used in circular ducts and are made of galvanized sheet metal with a thickness of 0.5 - 1 mm, resistant to moisture. The design of the valves is a metal body of circular cross section and a shutter. The shutter is controlled by a mechanism located on the side. If the position of the damper is manually adjusted, the model name contains the letter “P”, if the pneumatic actuator is connected, “P”, the electric actuator is “E”.
For small ducts, it is more convenient to use air vents with a manual drive. Large diameter valves are controlled by an electric actuator. Such valves change the intensity of the air flow or completely block its movement when the system stops. The valve flap can be held in position. It covers itself tightly and allows no more than 10% of air to pass through, as it is equipped with a sealant around the perimeter.
When adjusting the pressure, the damper is installed in a certain position. Round air valves for ventilation in the apartment and at the factory are produced with diameters of 25 - 125 cm. They are available in standard lengths of 5 - 7 cm, depending on the diameter. And throttles are 23.5 - 123.5 cm. According to GOST, they can be operated at a temperature of -30 ... +400 degrees Celsius, covered from snow and rain.
Rectangular Ventilation Valves
They are installed in rectangular ducts and are used at a temperature of -30 ... +70 degrees.The main material for their production is sheet aluminum, rectangular shutters are sealed with rubber tape. In accordance with the name - shut-off control valve, they can change the flow rate or completely shut it off.
The smallest rectangular throttle valves are available with a diameter of 15 x 15 cm, the largest 100 cm x 100 cm. For non-standard air ducts, valves are available on request. Since throttle valves can be a source of noise, it is not advisable to install models with a diameter of more than 500 mm in residential, medical and public buildings. The valve is mounted in the duct with a flange and nipple connection, and of a round shape and a retainer.
Valves with electric heating SVK-NS are produced in a rectangular shape. This is a housing with rotary blinds, at the joints of which heating tubes (electric heating elements). They prevent freezing of joints
Fire Ventilation Valves
Such valves are also called fire-retardant, installed in general ventilation systems. Together with the ventilation air lock system, it is mandatory according to the requirements of the fire inspection. They are necessary for the dense overlapping of channels leading through partitions, floors and walls of one floor. Fire dampers stop the spread of combustion products and fire from one room to another through air ducts. To reverse the movement of smoke in the opposite direction, air gates are designed in the ventilation system. They prevent the penetration of fire and smoke from the lower floors to the upper and are actually a branch of the duct down. Fire retardant valves are controlled through an electric actuator with remote control or automatically. The valve is equipped with a thermal sensor that transmits a signal via an electromagnetic drive to a spring lock, which slams the shutter. Such valves are installed in rooms of category "B" for explosion hazard. In rooms "A" and "B" only explosion-proof valves are used.
Smoke exhaust valves
Such equipment is installed in smoke ventilation ducts. The valves are located in the openings of the separating structures. Smoke exhaust air valves quickly remove smoke and combustion products from the fire zone, similar to ventilation air gates, reduce leakage into the smoke exhaust duct from fire-free floors. Thus, the removal of smoke is accelerated, fresh air is supplied to the premises.
Check valves for ventilation
Their difference is the presence of a spring that automatically closes the damper and shuts off the air supply in the opposite direction. Check valves are installed for ventilation into the duct by means of a nipple mount. They are made of steel with anti-corrosion coating, and the shutter is made of sheet aluminum. All air check valves for ventilation are general-purpose and explosion-proof. They are installed in vertical or horizontal position depending on the direction of air movement. Explosion-proof check valves for air ventilation have enhanced protection against fire and sparks. They are available in rectangular and round shapes, and are also used for air compressor ventilation.
Butterfly type check valves are distinguished by the central position of the axis on which the two shutters are mounted. When the fan is off, they stop the movement of air in the opposite direction. In the ventilation system of apartments most often install this particular type of air valve. See the video for more on this:
Filters for ventilation
The quality of atmospheric air supplied to buildings by ventilation systems is often unsatisfactory. In order to preserve people's health, it is necessary to clean the supply air.In production plants, it is often necessary to filter exhaust air, saturated with mechanical and chemical impurities.
Air is cleaned with air filters for ventilation. Filters are always installed in the ventilation systems of industrial enterprises, office complexes, medical centers, modern residential buildings.
Types of filters for ventilation
According to the principle of operation, air filters for ventilation are:
- bulk or absorbing;
- porous.
Absorbing bulk filters for air ventilation are filled with gravel, porcelain inserts, rubber crumb, activated carbon, metal crumb or coke. The material for the filler depends on the purpose of the building.
Porous air filters are created from strips with small holes, fabric or metal mesh. Sometimes they are saturated with oils.
To porous filters can be attributed and fabric: from cotton or wool.
Air filters have the ability to:
- rough cleaning - retain particles greater than 10 microns;
- fine cleaning - retain particles 1 to 10 microns;
- extra fine cleaning - particles retain 0.1 - 1 microns.
The shape and contents of the filter are dictated by its purpose. For example, for coarse filtration, a metal or synthetic mesh with impregnation is suitable. Such filter material is made in the form of individual inserts or bands.
Fine filters are usually made of fiberglass. They are folded, pocket and electrostatic. A widely used filler is activated carbon, which traps both mechanical inclusions, and stench, hazardous gases.
Extra fine filters are made of sheets of special submicron paper glued together or fiberglass.
In medical institutions, kindergartens and schools, combined multifilters are installed, capable of capturing all types of impurities.
Air filters for ventilation systems are available in the form of cartridges or panels that can be replaced. For convenience, the dimensions of the liners are standard. And the body is made to the diameter of the duct and can be rectangular or round.
Aerosol filters
This is a separate type of air filter for ventilation systems used in exhaust systems. Aerosol filters prevents the leakage of harmful products into the atmosphere. They are mainly used in the chemical and nuclear industries.
Aerosol filters provide perfect air purification in the premises of pharmaceutical enterprises and clean shops (where the most precise microcircuits are produced).
For air purification in ventilation systems, vortex traps, cyclones, bag filters, and apparatus for air-water washing are used as air filters.
