The air in the ventilation system occurs due to the movement of the air flow through the air ducts. Depending on the use of ventilating systems, air ducts for ventilation can be productive and domestic purposes. Their effectiveness is due to the rigidity, shape and diameter of the sections. The design of the duct can be flexible and rigid. To ensure maximum performance of ventilation systems, is familiar with the calculation methods of installation and maintenance of air ducts for ventilation.
- 1 air Ducts for ventilation: shapes structures and materials
- 1.1 materials for the manufacture of air ducts of ventilation systems
- 1.2 Types of cross-sections of ducts
- 2 How to produce calculations of air ducts of ventilation with natural ventilation
- 3 Features installation of ventilation ducts
- 3.1 installation of ventilation ducts
- 3.2 Methods of insulation of ventilation ducts
- 4 Methods of cleaning the ventilation ducts
- 4.1 measures for disinfection of air ducts of ventilation systems
Air ducts for ventilation: shapes structures and materials
Air ducts for ventilation is a system of pipes of various diameters and cross-sectional shape interconnected shaped elements. Correct selection of duct to a ventilation system depends on design features performance and design parameters, taking into account compliance with building and sanitary standards.
The materials for the manufacture of ducts of ventilation systems
Air ducts for ventilation, given the use of the materials for their manufacture, are divided into groups:
- metal. For their manufacture use galvanized or stainless steel. Their advantages are low weight, high degree of heat resistance, corrosion resistance, ease of installation;
- plastic. In the manufacture of such tubes as duct using polypropylene, polyurethane, polyvinyl chloride. Among their advantages is the absolute harmlessness, perfect sealing, easy installation and maintenance. They are easy to clean and quickly cleaned;
- corrugated aluminum. Air ducts for ventilation of corrugated aluminum pipe has been widely used because of the ability to compress and stretch in any direction and at the desired angle. Design flexible corrugated pipe is such that they retain the stiffness and cross-sectional shape. The advantages of flexible air ducts for ventilation are the lack of multiple connections, ease of installation and duration of operation;
- textile. Material for the manufacture of these duct ventilation – synthetic fabric (polyester). Mounts are also made of textiles. The fabric also prevents condensation forming on the surface of the duct and does not require insulation. Of the benefits – light weight fabric system, silent operation, flexibility, easy Assembly and disassembly. Cleaning fabric systems is performed by washing.
Types of cross-sections of ducts
The General forms of cross-sections of ducts are considered rectangular and circular cross-section. If the design of the ventilation system has limitations on the shape and size of the cross section for the ducts, use oval (elliptical) cross section.
A material of manufacturing of rectangular ducts for ventilation – galvanized steel. Wall thickness is applied depending on the size of the cross section and is regulated by the SNiP. Connect rectangular ducts with flange elements and without them. The standard length is 1.25 m, the maximum is 2.5 m. Thanks to its compact shape, rectangular structures embedded in space, limited in height (for example under the ceiling).
Material for circular ducts may be galvanized steel, plastic, metalized polyester tape with a spiral frame, PVC spiral skeleton, aluminum foil. The cross-sectional diameter varies from 100 to 1250 mm Connection flexible corrugated ducting for ventilation represent a dense castle. For easy transportation, corrugated flexible duct can be compressed by 5 times.
A useful tip! The choice of corrugated aluminum duct for use in ventilation system helps to significantly reduce the cost of purchasing fittings and the installation of the duct.
Possible multiple change the shape of the flexible corrugated air ducts do not violate their qualities. Spiral flexible design connected with flange elements and seals. Do not need additional insulation. Scope of flexible duct – supply and exhaust air in residential and industrial premises.
How to produce calculations of air ducts of ventilation with natural ventilation
To correctly calculate the diameter of the ventilation duct, it requires mapping the entire system of duct. It must contain dimensions of all rooms indicating their purpose. The calculation of the required amount of air produced in m3/h air Velocity in the system of natural ventilation is up to 1 m/s.
Calculate the size of ventilation ducts:
- the amount of air (L) – for the kitchen, this value is 90 m3/h, for toilet and bath 30 m3/h;
- the average air flow rate (V) is 0.3 m/s;
- the estimated dimension of the duct is made according to the formula:
F = L*V*3600 (the number 3600 is used for communication between the seconds and hours);
- to calculate the diameter we use the formula:
D = 2A in*(A+b), where D is the diameter of the cross section and the height and width of the duct.
Calculation of air ducts of ventilation:
- calculate the area of circular cross-section produced according to the formula:
S = π * D2 / 400, where
S – area of the actual cross section (cm2);
D – diameter of duct (mm);
- area calculation of rectangular cross section:
S = A * V / 100, where
S – area of the actual cross section (cm2);
And the height and width of the rectangular duct (mm).
Features of installation of ventilation ducts
Competent installation of ducts includes the following steps:
- the correct calculation of the cross-sectional area of the duct;
- the choice of an acceptable way of connecting the elements of the ventilation duct;
- calculating the number of fittings;
- to provide a method of insulation and sound insulation.
Mounting options ducting ventilation
Installation of duct systems involves the use of various fastening elements. Depending on the types of ductwork (round, rectangular, flexible) is calculated required number.
Types of ventilation, the advantages and disadvantages of ventilation systems, their device. The main parameters of the ventilation systems. The main components of ventilation.
As fasteners and connections can be: tie, adapters, elbows, crosses, plugs, reunite, etc.
A useful tip! To avoid additional costs for fittings and fixing of air ducts, it is recommended to use for the calculation of specialist ventilation installation.
- when mounting for attachment of a round duct using a coupling and nipple. Two elements of the duct connected with the part that is inserted into or mounted on the outside of the duct;
- the connection of the ducts with flange are made by means of a spring mechanism or by means of screws. When using the spring mechanism is simplified and reduced the installation of systems and provides reliable sealing. If parts of the duct is flanging, additional fixation is not performed;
- less frequently used method of fastening with brace (a device that is worn on beaded the ends of the duct). This method is simple and high level of integrity. But due to the expensive manufacture of tires not popular.
A useful tip! To reduce the noise of the ventilation system, the installation of ducts it is necessary to use fewer turns and transitions from one diameter to another.
- rectangular ducts for ventilation attached with hanging on the straps and on the traverse. Clamps are made from a metal strip traverses from the corner of steel;
- technology flange connection similar to the connection of a round duct to avoid sagging of the sides, the flanges are fixed with rivets;
- the connection with tyre is produced using a porous strip, pulling the mount lock. With this connection, the necessary clearances to handle the sealant.
Methods of insulation of ventilation ducts
To preserve the warm air in the room is recommended to make insulation of air ducts. In industry is used the insulation foam insulation which protects the ducts from heat loss and serves as insulation. For insulation of home exterior rectangular duct profile used foam and basalt wool boards, expanded polystyrene. The insulation is produced with a special adhesive and optional use of reinforcing foil tape.
For insulation of round ducts use roll materials: izolon, Isover. These materials have good insulating properties and fire safety. For insulation you can also use mineral wool, wrapped the duct in two layers.
Methods of cleaning the ventilation ducts
The efficiency of ventilation depends on the regularity of the cleaning of air ducts. Typically the cleaning process does not require dismantling of parts of the system. Allocate a mechanical cleaning method and chemical. Choose a purification method depending on the type of duct (flexible, semi-rigid, rigid) and type of contamination.
For the chemical method is characterized by the use of special aerosol formulations. They are used for cleaning the grease from kitchen ducts and industrial premises catering. Sometimes resorted to the method of cleaning by means of granules, which, passing through the air duct form the micro-explosion when in contact with a touch of fat. The chemical method of cleaning air ducts required a full tightness.
When mechanical cleaning of the ventilation ducts is used hydro-mechanical devices and vacuum pumps. The exit hole of the ventilation connect the vacuum pump and in the initial hole is placed a paddle and brush. In operation, the pump is mechanical cleaning of the duct rotating brushes, and all the dirt is collected in a special filter pump. Mechanical cleaning is difficult, but most effective way to clean ducts under intense pollution.
Measures for disinfection of air ducts of ventilation systems
When you finish cleaning, to disinfect ducts. Disinfection is performed to protect from harmful bacteria, dust mites, etc. For disinfection use special formulations (powders, liquids, aerosols), based on hydrogen peroxide. Disinfection are exposed not only to the duct system, but all of the elements of the ventilation system. You should also consider the purpose of the premises, the duct of which is being fumigated. Certain reagents may be allowed to use to disinfect the ducts of industrial premises and is prohibited for use in schools and institutions.
Typically, organizations that provide services for the maintenance of ventilation systems offer a full complex of works on diagnostics, cleaning and disinfection of air ducts.
Attentive and responsible approach to the installation, operation and maintenance of air ducts is a guarantee of long and trouble-free operation of the ventilation system.