Duct installation

1. Process requirements

1) Before installing the air duct, check the drawing with the construction site to check whether it can be installed according to the designed elevation and position;

2) Use infrared rays to position and set out the wires to ensure the distance and straightness of the air ducts, and find out the installation position of the suspenders according to the center line of the air ducts, and install the hangers;

3) After the size and angle of each part of the air duct system are confirmed to be correct, start to assemble and install. The connection of the air duct should be straight and not twisted, and the nuts of the connecting flange should be on the same side;

4) The gasket between the air duct and the air duct flange shall be a heat-resistant rubber plate with a thickness of 3mm or more. The gasket shall not protrude into the pipe or protrude from the flange, and the gasket shall not contain asbestos and other harmful components. , and should be resistant to oil, moisture, acid and alkali corrosion;

5) When installing the air duct, the center line of the air duct must be kept horizontal. After installing a section of the air duct, use a spirit level to measure the level; when the length of the air duct exceeds 20m, anti-shake brackets must be installed, and each system must have at least one pair;

6) When the air duct passes through the fire-proof and explosion-proof wall or floor that needs to be closed, a pre-buried pipe or protective sleeve should be provided, and the thickness of the steel plate is 2mm. The space between the air duct and the protective casing shall be sealed with non-combustible and non-hazardous flexible material;

7) For the installation of various air duct components and operating mechanisms, first check whether the valve shape and operating mechanism are intact, check the flexibility of the action, and confirm that all aspects of the valve are normal before installing. The installation direction and position should be correct. There should be at least 350mm clear space on the side to facilitate operation and maintenance; the fire dampers on both sides of the partition wall of the fire compartment should not be more than 200mm away from the wall surface;

8) The support and hanger of the fire and smoke exhaust duct must be set separately, and the support and hanger of the branch pipe, pipeline muffler, muffler elbow, and fire damper must be set separately;

9) After the air duct is installed, the tightness test should be carried out according to the system pressure level.

2. Key points of quality control

1) It is strictly forbidden to have sundries or other pipelines passing through the air duct, and do a good job of cleaning and protection;

2) The safety distance between the lower edge and outer edge of the support hanger and the live body of the catenary (including the catenary cable, the lower feeder, etc.) must be kept greater than 230mm, and it should be strictly implemented in accordance with the limit requirements;

3) The connecting bolts should be galvanized bolts, and must be equipped with corresponding flat washers, spring washers and nuts;

4) The working temperature of the flange gasket of the air duct is not less than 70°C; the working temperature of the flange gasket of the exhaust duct is not less than 250°C;

5) The allowable deviation of the horizontality of the air duct installation should not exceed 3mm per meter, and the total deviation should not exceed 20mm; the allowable deviation of the verticality of the vertical installation should not exceed 2mm per meter, and the total deviation should not exceed 20mm;

6) The air duct shall not be provided with an interface where it passes through the wall or floor. When the air duct is installed along the wall or floor, the distance from the wall or floor shall be greater than 150mm;

7) The installation of the electric actuator of the air valve must be fixed reliably, and it is strictly forbidden to place it on the air pipe at will;

8) For the installation of manual closed valve, the direction of the arrow marked on the valve must be consistent with the direction of the shock wave;

9) The configuration of the on-site air duct interface shall not reduce its effective section;

10) The support and hanger of the air-conditioning duct should be equipped with non-combustible heat-insulating pads to prevent cold bridges, and the heat-insulating pads should be anchored to the cross-arm when the support and hanger is manufactured;

11) For the detection of system air ducts, it is advisable to adopt the method of segmented detection and summary analysis. On the basis of strict installation quality management, the detection of system air ducts is mainly based on the main pipe and main pipe. When using the light leakage method to detect the tightness of the system, the air ducts of the low-pressure system shall have no more than 2 light leakage points per 10m joints, and the average number of joints shall not exceed 16 per 100m; It is qualified if there is no more than 1 light leakage point and no more than 8 joints per 100m.

3. Finished product protection measures

1) Handle and unload the air duct with care, do not drag it on the ground, and avoid bumping and tripping; do not damage the galvanized layer of the flange, and if there is any scratch, it should be completely repainted;

2) During the hoisting process of the air duct, the unconnected parts at both ends must be sealed with plastic film, and the upper air outlet of the air duct must also be sealed with plastic film before installation, and the transparent tape should be pasted to prevent dust from entering;

3) For the air ducts that pass through the equipment management room, the part that passes through the wall must be protected with a plastic film within 500mm from the wall to prevent the dust of the civil construction unit from polluting the air ducts;

4) It is strictly forbidden to pile up sundries on the installed air duct or stand on it for construction.

by Carol