In all large buildings need to ensure high-quality ventilation. To do this using passive air circulation is almost impossible due to the large volume of space. Therefore there is a need for a system of forced ventilation, important components of which are pipes. It on them air circulation.
Air ducts for ventilation systems should be easy, as mounted on the ceiling. For heavy construction needed a powerful attachment that is not always possible. The pressure in the system is small, so the ventilation pipe does not need thick walls that allows to make them lighter.
Ducts in direct contact with the air we breathe, and should consist of environmentally friendly material. It is also important to ensure the asepsis of the system in order to prevent the appearance in it of pathogenic bacteria.
Additional requirements are aesthetic appearance (ideally design should not be visible under the ceiling and wall panels), and resistance to accumulation of static charge.
The pipes for ventilation systems ↑
For many years in residential and industrial buildings using metal pipe. They are made of steel and aluminum alloys. Their advantages are:
- strength;
- durability;
- environmentally friendly;
- resistance to fire.
The disadvantage of metal is its tendency to rust. This problem is solved by using galvanized steel and using stainless steel alloys.
Another minus – the weight of the structure. It can be eliminated by reducing the thickness of the walls of the ducts. As mentioned above, the ventilation system is not particularly demanding on strength. Another drawback is that such pipes can accumulate static electricity. Metal ducts on the inner surface always remains a slight roughness that increases the resistance to air flow and requires additional power discharge.
Metal structures are noisy. Any alloy good conductor of sound. Fan noise, electric motor or air flow is often heard throughout the building. The sound travels through vents.
Relatively recently appeared on the market of PVC pipe. Their advantages are:
- ease;
- strength;
- low sound conductivity;
- no static electricity;
- corrosion resistance.
Theoretically, the plastic should last forever. But compared to metal it has a higher fire hazard. PVC does not burn, however, at high temperatures can release toxic substances which go directly into the air.
Design PVC have a perfectly smooth internal surface that reduces resistance to air flow and increases throughput. Plastic pipes are better suited for installation in industrial plants, where there is a aggressive environment, for example, the air containing acidic or alkaline vapours. The metal in these conditions is susceptible to chemical corrosion, and PVC is an inert material. Plastic channels characterized by ease and speed of installation, does not require welding.
The following is video guide to the installation of plastic ducts
They are made of PVC or polyurethane hard or medium type. Perhaps the use of multilayer pressed paper impregnated with synthetic resins, but this material is afraid of water. It cannot be used in high humidity areas.
Today, almost all ventilation systems are assembled from PVC tubing. The only exceptions are some industrial enterprises, for example, metallurgical factories, where ventilation is at a high temperature. At such facilities installed steel or aluminum ducts.
Used tubes of magnetic inorganic compositions with the addition of fiberglass. They combine the advantages of plastic and metal construction – resistant to all types of corrosion, lightweight, durable, do not burn and are not afraid of moisture.
Features shape and mounting of the air pipes ↑
Ducts can be round, rectangular or oval cross-section. Form is selected based on the specifics of the ventilation system.
Tube of rectangular cross section compared with the round are easier to install and more compact, but worse leak air. It would make for a more efficient forced ventilation.
Design round and oval cross-sections can be longitudinally welded and spiral.
The latter is more durable due to the stiffeners, located along the entire length, but are much more expensive due to increased material consumption during manufacture. Spiral channels should be used on long straight sections of ductwork. Construction with low rigidity in such cases, can SAG under its own weight.
Rectangular pipes are only pipes. When using the straight length of the highway should not exceed a few meters, to avoid sagging and deformation. Rectangular ducts are available in the form of separate sections connected by welding or flange locks. Possible docking with the use of metal rails.
For some sections of the ventilation system required corrugated semi-rigid pipe with a variable shape. They are made of aluminum tape, stretched over a steel wire frame with ribs large cross-section. These channels can be bent to almost any angle, which is convenient when mounting the rotary sections of the ventilation trunk. High flexibility allows the use of semi-rigid structures only in short sections.
The cheaper option of corrugated design is its plastic counterpart without the wire frame. Gofra PVC is lighter and non-corrosive, but flammable, so it cannot be installed in areas with high temperature. Usually plastic is not so durable as steel, but for rough conditions you can use the corrugation of polyvinyl chloride extra heavy type. She has considerable mechanical strength not less than 1100 N per 5 centimeters of length.
When a ventilation device within a single building commonly used highway in different shapes and designs for optimal efficiency of the exhaust air.
When installing duct in the living spaces you need to consider several important points. The vent line shall be of aesthetic appearance, and ideally even hiding under a ceiling or wall panels. If you hide the channel is not obtained, it is necessary to use a plastic pipe of rectangular cross section. It is more compact and fits better in the interior. It is advisable to choose a duct with the same color as the surrounding wall. In residential areas it is difficult to establish large and noisy fan for forced discharge of the air, but the small size of private homes restrict passive ventilation without the use of superchargers.
In addition to the above-described constructions, in residential premises it is possible to mount the ducts of thick-walled cast-iron channels which are commonly used in sanitation. Their main advantage – the price is much less than that of aluminum and plastic counterparts.
In the simplest version of a cast iron ventilation is a tube with a protective cover protruding from the roof or from the cellar.
This construction has many drawbacks – the large mass, complexity of installation (there can not do without gas welding) and ugly appearance. Cast iron subjected to severe corrosion, so over time the channel can become clogged with rust. Today these highways are not used.
You can make a duct from plastic sewer channel.
He, too, is much cheaper than the vent pipe, but compared to iron is lighter, easier to install and more durable.
If necessary, insulate the ventilation, you can use the sandwich pipe. This is the usual metal or plastic ducts wrapped with insulation, usually mineral wool. The existing roads difficult to insulate with any insulation material.
Device effective ventilation system requires careful calculation, determine the type and quantity of required materials, competent installation. The result of this work should be clean and fresh air in a residential building or production facility.
