The system of the jointed pipes on which gas is supplied or taken away is called air duct. As a rule, air ducts are used for the organization of ventilation and air conditioning systems.
Big distribution has received use of air ducts of welded type for the organization of ventilation systems in houses and industrial premises. They are made from sheet steel which thickness no more than two millimeters. Different can apply steel: it can be rolled, hot-rolled, galvanized. Air ducts from gofrotruba gain popularity, they are plastic and can precisely repeat all bends of walls of the room. And here plastic go out of use in view of their high fire danger and low resistance to the corrosive external environment.
Welded air ducts are connected by means of welding technology, t.e of fastening of metal by means of high temperature of melting.
Thickness of welded air duct is defined on stages of creation of the project of vent system and depends on intensity of air stream, volume of gas, length of communications and so forth.
Types of air ducts
Welded air ducts can be different types. Those which possess circular and rectangular cross section are the most widespread. Air ducts which thickness of metal is equal to about two millimeters belong to the first group. Metal with thickness to 1 millimeter is applied to rectangular welded air ducts. Also fire-resistant air ducts of welded type meet in the market. They possess durability increased by degree. For ensuring protection against flame ventkorob cover with special solution. Norms have provided production of such air ducts only from black steel material, in some situations the production from steel of corrosion-proof type is possible, but its thickness should not be less than 0.88 millimeters. However air ducts of fire-resistant view with metal thickness not less than 1.5 millimeters are more widespread, they belong to class "P". Their basic purpose is use in conditions when static pressure very high and also for movement of air streams in corrosive medium.
There are 2 classes of air ducts: those which have normal degree of durability belong to class "H". Normal welded air ducts belong to this class. Class "P" unites dense air ducts of welded type.
Choice
Welded air ducts of rectangular and round types meet rather often. Round are made easily and cost not much, their use is economic. They are not suitable for mounting in rooms with bends and with limited installation site. In similar rooms it is the best of all to apply welded air ducts of rectangular look. They can be stretched, without having broken section. They are more expensive, but it is much simpler to use them when mounting, besides installation of rectangular pipes happens much quicker, and forming of ventilating boxes is not required at all.