Suzhou Qiao Hui HVAC introduction: What are the selection standards for air duct materials?

The materials used in Suzhou ventilation pipes should be selected according to the requirements of the project. Commonly used materials are the following: sheet metal, sheet metal is the main material for making air pipes and components. Ordinary thin steel plate, has good processing performance and structural strength, often used in general ventilation duct and dust duct. Its surface is easy to rust, should be painted for anti-corrosion.

Galvanized steel plate is galvanized by ordinary thin steel plate, and the surface is protected by zinc layer to prevent rust. Because of its silver-white surface, it is also called "white iron sheet". Sheet iron generally has a thin thickness and is commonly used in air conditioning systems without dust wear in the gas and in humid environments that are not affected by acid fog.

Aluminum and aluminum alloy plate, good processing performance, corrosion resistance, friction is not easy to produce sparks, but the cost is high, often used in explosion-proof ventilation systems. Stainless steel plate, with good corrosion resistance, its cost is high, only in the higher requirements for corrosion resistance, such as ventilation pipes in chemical systems.

Non-metallic materials, there are many types of non-metallic materials used in ventilation pipes, but their application is not as common as sheet metal. Hard polyvinyl chloride, acid, alkali and corrosion resistance, good machining performance, smooth surface, convenient construction. It is often used in ventilation systems with corrosive gases.

However, hard PVC is not resistant to high temperature, the use temperature is generally not more than 60 degrees, the coefficient of linear expansion is large, and it is not easy to aging and fire prevention. Glass fiber reinforced plastic, which is made of glass fiber products as reinforcement material, resin as binder, through a certain molding process of composite materials. Corrosion resistance is good, often used in corrosive gases and exhaust systems containing water vapor.

Plastic composite steel plate, which is sprayed on the surface of ordinary thin steel plate with a layer of 0.2-0.4mm thick plastic layer. It is commonly used in air conditioning systems with high dust requirements and corrosion resistance systems of -10 ° C to 70 ° C. The price of this steel plate is higher, 50% more expensive than ordinary carbon steel plate. Brick and concrete, which are common building materials, are often used to utilize building space or lay underground air ducts.

Sheet steel: general ventilation and air conditioning system: 0.5~1.5mm; Dust removal system: 1.5~3.0mm. Plastic panels: Ventilation systems containing corrosive gases. Inorganic glass steel: the occasion of high humidity. Various hoses: metal, plastic, some with insulation layer. Composite duct: double aluminum foil with phenolic resin, single aluminum foil with glass fiber, others.

New flexible air duct system: excellent: air distribution is uniform, avoid blowing; Light weight, convenient installation, low structural requirements; Flexible, easy to change the system; Easy to clean. Because the cold and heat loss is too large, the heat preservation is not reasonable economically; Due to the loss of cold and heat, the temperature of the medium cannot reach the temperature required by the design.

Due to heat loss, the temperature of the gas transported in the duct is reduced to the point where it is likely to condense or freeze in the duct or in the subsequent dry dust collector; Due to the loss of cooling capacity, condensation occurs on the outer surface of the duct. Due to the transmission of high temperature gas, the outer surface temperature of the air duct is too high (such as greater than 50 ° C), which will cause injury to the operation and maintenance personnel, or will cause gas, steam, dust, and fire.

The specific requirements of thermal insulation materials are: small thermal conductivity, generally not more than 0.23W/m·K; The porosity of the material is high, the density is small, and the density is generally not more than 600kg/m3; Has a certain compressive strength, not easy to deformation; Small hygroscopicity, no corrosion on pipe wall; Flammable materials should not be used, otherwise anti-corrosion and fire prevention treatment should be carried out.