The air duct is part of the ventilation system of the house and of each apartment in particular. Its main function is the inflow or outflow of air masses. There is a large selection of different types of air ducts, which have their own characteristics. The classification is made according to various criteria, including the shape of the cross-section, material, method of connection and other parameters. To choose the right system for your home, you should familiarize yourself with the characteristics of each.
Duct classification
Air ducts are special ventilation ducts that direct air flows in a given direction. They have the ability to adjust the pressure and air flow rate. The channels themselves are a complex system with a large number of branches and elements: hoods, fans, filters, air conditioning.
The criteria by which air ducts can be divided are related to their design, purpose and features of work.
Sectional shape
According to the cross-sectional shape, the following types of air ducts can be distinguished:
- Rectangular and square. This is the traditional look and is most often used in apartment buildings. They are more practical, but swirls can be created at the corners. Flat ducts also belong to rectangular systems. They are practically invisible to the eye, but they are able to pass a small volume of air masses.
- Round. They have a smooth profile so that no eddies are generated. Lungs. Quiet operation. They are mainly used in large industrial buildings. The diameter depends on the volume of passing air. They are characterized by low weight and reduced material costs.
The cross-sectional area is also different for each ventilation. The dimensions of the air ducts are selected individually for different premises.
Method of connecting parts to each other
The pipes need to be connected to each other. On this basis, there are:
- Welded. The contact is made by welding. This is the most reliable and sealed, but the most time-consuming method of joining parts due to the complexity of the process and the need to use a welding machine.
- Flanged. The parts are connected using flanges. This is a method with good tightness and reliability. Requires special skills from the master when connecting. The most common contact method.
- Coupling. The connection is made using special pipes.
- Bell-shaped. They differ in assembly speed and ease of installation. The tightness is low.
- Bandage. Used to connect round ducts.
Also, the types of connection include diffusers (expanding the air flow) and confusers (reducing the flow), tees, adapters, elbows and duct taps.
The result of the connection is monitored by carrying out commissioning works. The tightness of the system and the absence of blowing are checked.
Pipe material
According to the material, air ducts made of stainless steel, galvanized steel, aluminum, PVC, metal-plastic, vinyl plastic, fiberglass are distinguished.
Steel models are durable, robust and corrosion resistant. They do not require additional maintenance, reduce operating noise and pressure loss. The use of stainless steel allows the working temperature to be increased up to 500 ° C.Sheet thickness is usually up to 1.2 mm. The main area of application is in plants with heavy industry and high background radiation.
Galvanized models are suitable for use in temperate climates without aggressive environments. The maximum temperature is limited to 80 ° C. Thanks to the zinc coating, the pipes are protected from corrosion, which prolongs their service life. Mold and mildew do not form on the walls. They are used in rooms with high humidity (basements, attics, baths, bathrooms, kitchens).
Plastic air ducts are also popular for their low cost, lightness, strength, ease of transport, and no rust. Resistant to various chemical compositions and compounds. The main area of application is chemical production, pharmaceutical and food industries.
Aluminum pipes are flexible and highly durable. They maintain low and medium pressure in all systems and chimneys. They have good temperature resistance.
Reinforced-plastic pipes are made of two layers of metals, between which foam plastic is laid. This is a structure with improved strength characteristics with low weight and aesthetic appearance. No additional thermal insulation required. The disadvantages include the high cost.
Polyethylene is used in supply ventilation systems. Fiberglass has found its application for the joint of fans and air diffusers. In an aggressive environment, vinyl plastic is used, which has the highest corrosion resistance, low weight and the ability to bend to any angle.
Purpose and design features
Pipelines are distinguished according to their purpose:
- flexible corrugated;
- semi-rigid;
- thermally insulated;
- fire retardant.
This classification is also related to the scope of the pipe. The fire retardant duct system is used only in hazardous areas. Rigid and flexible air ducts are used in houses. In this case, the main part of the system is made exactly rigid, and a corrugated pipe can be brought out to connect various devices.
By design, air ducts are longitudinal, spiral-wound, spiral-welded. Longitudinal seams are also called industrial. They are made from steel sheet with a thickness of 0.55-1.2 mm. Rectangular ducts have a seam at the fold, which gives extra strength and rigidity. Spiral-welded models are made from special steel belts that have an anti-corrosion coating. Thickness 0.8-2 mm. There are no length restrictions. The joints are overlapped, so the seam is durable and reliable. For spiral locking systems, steel belts with an anticorrosive coating with a thickness of 0.5-1 mm are selected. The length of the tape can be any. The average width is 130 mm.
Other parameters
Pressure and air velocity criteria are also important when choosing a system. Devices below 900 Pa refer to low pressure installations, from 900 to 2000 Pa - medium, and over 2000 Pa - high. Low-speed air ducts have an air speed of up to 15 m / s, and high-speed ones from 15 m / s. In small rooms, low-speed, low-pressure systems are installed. Other types of ventilation ducts are used in high-rise buildings and industrial premises.
Scope of application
The main component of any ventilation system is the air duct. Round and rectangular ducts are used to transport air and gas mixtures. The devices have found their application in the following areas:
- industrial enterprises;
- food and pharmaceutical industry;
- medicine;
- catering establishments;
- household purpose;
- laundries, boiler rooms;
- administrative and office premises.
Air ducts are selected for each type of premises depending on the conditions: temperature, humidity, presence of chemicals, fire hazard, explosion hazard.
Installation features
According to the joint venture, the installation of air ducts should be carried out taking into account the following features:
- Flexible products are laid only after they have been fully stretched.
- The sleeves must be fastened in such a way that they do not sag. Otherwise, vortices and places of stagnation of air masses will be created.
- It is forbidden to mount flexible and semi-flexible products if the vertical section covers more than two floors.
- In places of contact with the ground, in concrete structures, on basements, only rigid pipes are allowed.
- Pipes are laid through the walls only with the use of special metal sleeves and adapters.
If there are no skills and tools, the installation of the ventilation system must be entrusted to specialists.
