Installation requirements for various air ducts in ventilation and air conditioning engineering

2023-02-02

Installation requirements for various air ducts in ventilation and air conditioning engineering

△ Metal air duct installation requirements

(1) Air duct extension and hoisting. First of all, according to the specific conditions of the site, select two reliable hanging points on the beam and column, then hang the chain or pulley, and bind the air duct firmly with hemp rope. When lifting, when the air duct is 200~300mm above the ground, stop hoisting, carefully check the stress point of the chain or pulley and the rope binding the air duct, whether the rope buckle is firm, and whether the center of gravity of the air duct is correct, and then continue to lift.

After the air duct is placed on the support and hanger, connect all the cross-arms and suspenders, and confirm that the air duct is stable, and then you can untie the rope buckle and remove the rope.

(2) The air duct is installed in sections. When the quality of the air duct is light, the installation is not high, and it is inconvenient to hang the pulley, or it cannot be hoisted due to site restrictions, the air duct can be pulled to the scaffold in sections with ropes, and then lifted to the bracket to align the flanges and install them section by section.

(3) When the air duct is laid in the ditch, if the ditch is wide enough to install the flange bolts, it can be connected in sections in the ditch. The pipe is tied up and slowly placed on the bracket of the trench.

When the air duct in the trench is connected to the air duct on the ground, or passes through the floor, in order to facilitate the connection with the air duct on the ground, the distance between the interface of the air duct protruding from the ground and the ground should not be less than 200mm.

When installing the air duct in the trench, the inside should be kept clean. After the installation is completed, the exposed opening should be temporarily blocked to prevent debris from falling into it.

(4) The horizontally installed air duct can be aligned and leveled with the adjusting bolt on the hanger. The air duct with thermal insulation pads is allowed to be slightly adjusted by the thickness of the pads, but the pads cannot be canceled due to adjustment. The straightness of the air duct connection is checked with a wire rope, and the vertical air duct is checked with a hanging wire. When the air duct is twisted, it can only be adjusted by reassembling the flange. The level or slope of the air duct can be checked with a spirit level, and it cannot be adjusted by stuffing more gaskets on one side of the flange.

Metal air duct

△Composite material air ductinstallation requirements

(1) The hanger of the composite material air duct adopts angle steel as the cross arm, and the connection between the air duct and the galvanized steel air duct with flange and other components should use special transition connectors.

(2) The air duct is connected to the air outlet, and the inner side of the air outlet is mostly connected with self-tapping screws. The end of the air duct or the open end of the air duct should be inlaid with a mouth-shaped connecting strip, and then connected with self-tapping screws. When the upper opening of the main air duct is connected to the branch air duct, special aluminum alloy flange strips are inlaid on the connection ends, and the aluminum alloy inserts are inserted after alignment; the opening should be straight and the size error is 1mm. After the air duct connection is inserted into the cutting strip, the holes at the four corners of the connection should be sealed with sealant. When flange connection is adopted, measures to prevent cold bridges shall be taken.

(3) The joints of composite air ducts should be firm without holes and cracks. When using plug-in connection, the interface should be matched without looseness, and the port gap should not be greater than 5mm. When using flange connection, there should be measures to prevent cold bridge.

△Flexible duct installation requirements

Non-metallic flexible air ducts should be installed away from heat source equipment. After the flexible air duct is commissioned, it should be able to fully stretch, and the stretch should be greater than or equal to 60%. The cross-section of the air duct shall not be reduced at the bend. For metal circular flexible air ducts, hoops should be used to fasten the air ducts to the flanges.

When directly fastening with screws, the distance between the fastening screws and the end of the air duct should be greater than 12mm, and the distance between the screws should be less than or equal to 150mm. The length of the aluminum foil polyester film composite flexible air duct used for branch pipe installation should be less than 5m. The air pipe is connected to the angle steel flange, and the air pipe and the flange should be fastened with a galvanized plate with a thickness greater than or equal to 0.5mm.

Flexible duct