The installation precautions for fire-resistant composite ducts are as follows:
Construction preparation:
Quality inspection: The quality and performance (including duct strength, air leakage per unit area, fire resistance limit, etc.) of the finished air duct production should be carefully inspected in the inspection report. Only after passing the inspection can it be used.
Positioning and laying out: Complete duct positioning, elevation, and technical review to ensure compliance with design requirements.
Hole reservation: The reserved hole position of the building structure should be correct, and the hole should be 100mm or more larger than the outer size of the air duct, corresponding to the installation position of the enclosure structure.
Manufacturing and installation of supports and hangers:
Material requirements: The fixing parts, suspension rods, cross arms, and all accessories of the support and hanger should meet the requirements of their load rating and application parameters.
Installation specifications: The suspension rod should be straight, the threads should be complete and smooth, and the nut and suspension rod buckle should be tightly engaged. The extension of the suspension rod can be achieved by using threaded or threaded connections at the end of the suspension rod, and anti loosening measures should be taken at both ends of the casing. When using a threaded rod, the threaded rod should not be directly installed on the expansion bolt, and galvanized threaded rods should not be extended in length by welding. The suspension rod cannot be directly connected to the bolt, and should be connected through steel sections such as angle steel or channel steel. Rust removal, oil removal, and painting are not allowed. The exposed parts of the supports and hangers need to be treated with anti-corrosion measures.
Position requirement: When installing rectangular air ducts horizontally, the spacing between supports and hangers should be calculated and determined based on the weight of the ducts, components, and valves. The support and hanger should be evenly stressed and have no obvious deformation. The deflection value of the cross arm of the hanger should not be less than 9m. When the inner edge length of the air duct is not greater than 400mm, the spacing is not greater than 2400mm; When the inner edge length of the air duct is not greater than 1250mm, the spacing is not greater than 2200mm; When the inner side length of the air duct is greater than 1250mm, the spacing should not exceed 1800mm. The gap between the rectangular air duct facade and the suspension rod should not exceed 150mm. Support hangers should not be installed at air vents, inspection ports, or operating parts of valves and automatic control mechanisms, and should not be less than 200mm away from the air vents. The distance between the support and hanger at the end of the air duct should not be greater than 1000mm, the distance from the starting point of the horizontal elbow should not be greater than 500mm, and the distance between the support and hanger installed on the branch pipe and the main pipe should not be greater than 1200mm. Both ends of the contact surface between the horizontally installed air duct and the support hanger should be equipped with galvanized angle washers with a thickness greater than or equal to 1.0mm, a width of 60-80mm, and a length of 100-120mm. When the length of the straight air duct is greater than or equal to 1000mm, no less than 2 fixing points should be set. The vertically installed air duct bracket should be set at the flange connection, and it is not advisable to fix the air duct separately in the form of clamps. Steel brackets should be used to allow the weight of the air duct to act on the bracket through the flange, and the flange should be connected in the form of an angle steel flange. Horizontal suspended main air ducts or system air ducts with a length exceeding 20m should be equipped with at least one anti sway support hanger or fixed point to prevent swinging.
Connection and sealing:
Connection method: The air ducts, valves, air vents, etc. are all connected by angle steel flanges. The static pressure box and axial flow fan are connected by C-shaped channel steel (or angle steel) flanges. The air duct connection should be firm and tight.
Bolt requirements: The bolt should correspond to the flange. In outdoor and humid environments, the bolt should have corrosion protection measures or use galvanized bolts. The connecting bolts of the flange should be tightened evenly, and the nuts should be on the same side.
Material selection: The flange gasket should be made of non combustible, high temperature resistant and fireproof materials, with a thickness of 3-5mm. The flange gasket should reduce splicing, and the joint connection should be in a stepped or mortise and tenon shape. The gasket should not protrude into the pipe or fall off, and should cover the flange and the end face of the air duct plate. The smoke exhaust duct should use non combustible A-grade sealant.
Installation inspection:
Tightness inspection: After the installation of the composite air duct system, the main and main air ducts should be inspected for tightness in sections, and should comply with the relevant provisions of the current national standard "Code for Acceptance of Construction Quality of Ventilation and Air Conditioning Engineering" GB 50243 and the current industry standard "Technical Specification for Ventilation Ducts" JGJ/T 141. The installation and acceptance of composite air ducts used for smoke control and exhaust systems should also comply with the relevant provisions of the current national standard "Technical Standard for Building Smoke Control and Exhaust Systems" GB 51251.
Other precautions:
Cleaning and protection: Ducts, static pressure boxes, and other components must be wiped clean to ensure no oil stains or floating dust. When construction is stopped or completed, the ports should be sealed. Before installing the air duct, internal and external debris should be removed, and cleaning and protection work should be done well.
Dimensional deviation: The allowable deviation for the outer diameter or outer length of the air duct is 2mm when it is less than or equal to 300mm; When it is greater than 300mm, it is 3mm. The allowable deviation for the flatness of the pipe mouth is 2mm, and the difference in length between the two diagonal lines of a rectangular air duct should not exceed 3mm; The difference between any two orthogonal diameters of a circular flange should not exceed 2mm.
Fire prevention measures: When the fireproof board air duct passes through a fireproof or explosion-proof wall or floor that needs to be sealed, the gap between the air duct and the reserved hole should be tightly sealed with non combustible flexible materials. The distance between the fire damper and the wall shall not exceed 200mm, and separate supports and hangers shall be installed for fire dampers with a large side length b ≥ 630.
Safe construction: Wiring in the construction area and wiring of construction equipment should be carried out by on-site electricians and operators. It is strictly prohibited to connect or pull without authorization. All kinds of machinery should be strictly operated according to the operating procedures. When operating the cutting machine, protective measures must be taken and qualified personnel must operate it.