There are the following 6 types of air duct fittings commonly used in ventilation ducts, and their functions are as follows:

1. Flange

Flanges are used to extend the connection between air ducts of ventilation ducts and between air ducts and accessories, and can increase the strength of air ducts. According to its cross-sectional shape, it can be divided into rectangular flange and circular flange.

2. Valve

The valve in the ventilation system is mainly used to start the sail, close the air duct and air outlet, adjust the air volume in the pipeline, balance the resistance, etc. The valve is installed in the air duct of the fan outlet, the main down air duct, the branch air duct or before the air distributor. Commonly used valves are plug-in valve and butterfly valve.

3. Flexible short tube

In order to prevent the vibration of the fan from being transmitted to the room through the air duct and causing noise, flexible short pipes are often installed at the inlet and outlet of the fan, with a length of 150-200mm. Generally, the flexible short pipes of the ventilation system are made of canvas, and the ventilation system for conveying corrosive gases is made of acid-resistant rubber or 0.8-1.0mm thick PVC plastic cloth.

4. Elbow

Elbows are fittings used to change the direction of ventilation ducts. According to its cross-sectional shape, it can be divided into circular elbow and rectangular elbow. Radius of curvature and number of mid-sections for 90° elbows

5. Tee

A tee is a bifurcated or convergent fitting of a ventilation duct. According to its cross-sectional shape, it can be divided into circular tee and rectangular tee.

6. Bend back and forth

Bends are used in ventilation ducts to cross or get out of the way of other ducts and building elements. According to its cross-sectional shape, it can be divided into circular back-and-forth and rectangular back-and-forth.