Ventilation duct information: Thin steel sheet, plywood, fiberboard, brick and concrete can be used as air duct information. Thin steel sheet is the most commonly used material. It is divided into ordinary steel sheet and galvanized steel sheet. Steel sheet with thickness of 0.5-1.5mm is used in general ventilation and air conditioning system. PVC board can also be used as air duct data. It is bright, dust-free and corrosion-resistant. It is sometimes used in air-conditioning projects. But the cost of construction and installation is high. In recent years, there is also the use of exterior disposal of glass fibreboard wind pipe data, it has both noise and thermal insulation effect.
1. Sheet steel air duct. It is advisable to use low carbon steel sheet to make ventilation pipes with thin steel sheet, and cold rolled steel sheet is most suitable for ventilation and air conditioning engineering.
The thin steel plate air duct with thickness less than 1.2mm is joined by bite and welded with thickness less than 2mm. According to the relevant rules, when the side length of rectangular air duct is greater than 630 mm and the side length of insulating air duct is longer than 800 mm, the reinforcing measures should be taken for both thin steel air duct and galvanized steel air duct. Angle steel is usually used to reinforce air duct, and some reinforcement methods, such as lifting joint (vertical bite) or rolling groove on the wall of air duct, are used to reinforce the air duct. Angle steel or flat steel flange is usually used to connect air duct with air duct.
2. Galvanized steel air duct. During the construction of galvanized steel sheet, attention should be paid to keeping the galvanized layer from being destroyed, and bite and riveting should be adopted.
3. Stainless steel plate air duct. In processing, scratches, scratches and depressions on the surface of the sheet should be avoided, and hammers should not be used to knock, so as to prevent the destruction of the crystal structure of alloy elements, otherwise there will be corrosion centers where hammers strike. Stainless steel has high strength and good elasticity. When the thickness of pipe wall is more than 0.8mm, welding is usually used. When the thickness is less than 0.8mm, bite joint is used. The flanges used for connecting stainless steel air ducts are usually cut into strips, rectangular flanges can be welded according to size, and circular flanges are processed by cold bending method.
4. Aluminum plate air duct. Sparks do not occur when friction occurs, so they are often used in explosion-proof ventilation systems.
The bite moulding of air duct should adopt wooden hammer or square ruler as far as possible. In order to prevent the deformation of bite joint, it is better to use mechanical forming. When the thickness of aluminium sheet is more than 1.5mm, gas welding or nitrogen arc welding can be used.
Aluminum and aluminium alloys will produce electrochemical corrosion when they contact with iron and copper. Therefore, aluminium flange should be used as far as possible in air duct of aluminium plate. If common angle steel flange is used, zinc plating or anti-corrosion insulation treatment should be done, and aluminium rivet should be used in riveting.
5. Composite steel plate air duct. It is often used in air conditioning systems with high dust-proof requirements and air ducts of corrosion-resistant systems at temperatures ranging from - 10 C to 70 C. This kind of air duct should be careful not to destroy the plastic layer during processing, and its connecting method can only be biting and riveting.
6. Air duct of rigid PVC plastic sheet. Hard polyvinyl chloride plastics have good chemical stability, which is stable to various acids, bases and salts, but unstable to strong oxidants and concentrated nitric acid, fuming sulfuric acid, aromatic hydrocarbons and chlorinated hydrocarbons.