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Operation process of air duct installation
First, find out the air duct elevation according to the design requirements and refer to the civil engineering datum line.
Second, make hangers and high hanging points.
1. After the elevation is determined, determine the form of the air duct support and hanger according to the spatial location of the air duct system.
2. The production drawings of air duct supports and hangers are made according to the material specifications and methods of "Construction and Installation Atlas of Construction Equipment" (91SB6).
3. Setting of lifting point:
Embedded parts method:
(1) Embedded in the early stage: Generally, the reserved personnel will firmly fix the embedded parts on the steel bars of the civil structure according to the coordinate position on the drawing and the distance between supports and hangers.
(2) Pre-embedded in the later stage: Embed the bracket on the brick wall: calculate the distance from the surface of the bracket steel to the ground according to the elevation of the air duct, find the correct installation position, and drill a square hole of 80mm×80mm. The inside and outside of the hole should be the same size, and the depth should be 30-50mm larger than the depth of the bracket embedded in the wall. After the hole is drilled, wet the wall hole with water and wash out the brick chips in the hole. Then fill a part of 1:2 cement mortar in the wall hole first, and embed the bracket. The embedment depth is generally 150-200mm. Level the bracket with a level, adjust the buried depth, continue to fill in the mortar, and properly fill in some water-soaked stones and broken bricks to facilitate fixing the bracket. When filling in cement mortar, it should be slightly lower than the wall surface, so that civil engineering can carry out wall surface decoration.
Embed the hanger under the floor: After confirming the location of the elevator, use a percussion drill to drill a hole in the floor, and then cut a 300mm long and 20mm deep groove on the ground. Insert the hanger into the groove and fill the groove with cement mortar.
Third, install the hanger.
1. According to the center line of the air duct, find out where the suspenders are laid. The single suspenders are on the center line of the air duct, and the double suspenders can be installed symmetrically according to the screw hole spacing of the pallet or the center line of the air duct.
2. According to the form of the hanger, the boom can be welded or hung on the hanger, and should be coated with anti-rust paint after welding.
3. When the air duct is long and a row of brackets needs to be installed, the two ends can be installed first, and then the brackets at both ends can be used as the reference, and the elevation of the middle bracket can be found by the wire drawing method for installation.
4. When installing the standpipe clamp, first fix the uppermost pipe fitting, and then use a wire hammer to hang the wire at the center, and the lower tube clamp can be fixed according to the wire.
Fourth, the spacing of air duct supports and hangers.
If there is no design requirement for the distance between air duct supports and hangers, the non-insulated air ducts shall meet the requirements in the table below. If there is no design requirement for the spacing of thermal insulation ducts, supports, and hangers, multiply the spacing requirements in the table below by 0.85. The distance between the support and hanger of the spiral duct can be increased appropriately.
Fifth, air duct arrangement and installation.
1. Flange connection:
(1) In order to ensure the tightness of the flange interface, there should be gaskets between the flanges. In the absence of special requirements, flange pads are selected from the table below.
(2) When the flanges are connected, it is required to specify the gasket, align the two flanges, put on the bolts and put on the nuts, (note: the nuts should be on the same side), do not tighten it until all the bolts are put on , and then tighten the bolts. Double-press the air duct, the flanges at both ends should prevail, and pull the wire to check whether the air duct connection is straight.
(3) Matters that should be paid attention to when padding flange padding and flange connection.
① Correctly select litter materials and avoid using wrong litter materials.
② The surface of the flange should be clean and free of foreign matter.
③ Flange pads cannot be squeezed into or protruded into the pipe, otherwise it will increase the flow resistance and increase the dust accumulation in the pipe.
④ After the flanges are connected, it is strictly forbidden to fill the gaps of the flanges with gaskets.
⑤ The nuts connecting the flanges should be on the same side.
⑥ Bolts used for stainless steel flange connections should use stainless steel bolts of the same material.
⑦ Galvanized bolts shall be used for the flange connection of the aluminum plate air duct, and galvanized washers shall be placed on both sides of the flange.
⑧ Galvanized bolts are used for the connection between the PVC air pipe flange and the FRP flange.
2. There is no flange connection for air duct arrangement
① Hoop connection: It is mainly used for the connection of steel plate round air ducts and spiral air ducts. Firstly, the two ends of each pipe section are rolled out with ribs, and one end is shrunk to a small opening. When installing, insert the small opening into the large opening according to the direction of air flow, use steel hoops to connect the drum hoops at both ends tightly, and finally use bolts to pass through the middle of the earrings and tighten them.
② Plug-in connection: mainly used for rectangular or circular air duct connection. Make the connecting pipe first, then insert the air pipes on both sides, and then fix it tightly with rivets.
③ Plug-in connection: mainly used for rectangular air duct connection. Insert different types of cuttings into both ends of the duct and compact them.
④ Hose type connection: mainly used for the connection of air pipes and components (such as radiators, air outlets on the side of the static pressure box, etc.). When installing, the two ends of the hose are sleeved outside the connected pipe, and then the hose is clamped tightly with a special soft clip.
Sixth, the air duct is installed in place.
According to the site conditions, it can be connected to a length on the ground and placed in place by hoisting, or the air ducts can be placed on the brackets one by one and connected one by one. The general order is to dry the pipe first, then branch the pipe. The installation of the riser is generally installed from the bottom up. After the installation is in place, perform leveling and alignment to meet the design requirements.
Issues that should be paid attention to when installing air ducts:
1. When the air duct is connected without flange, the interface should be tight and firm. The four corners of the rectangular air duct must be positioned and sealed. The two planes connected by the air duct shall be straight and shall not be dislocated or twisted.
2. The circular air duct installed on the bracket should be provided with a bracket.
3. A rainproof cover should be installed outside the air duct passing through the roof.
4. Air ducts that are prone to condensed water should be installed according to the slope required by the design. There should be no longitudinal seams at the bottom of the air duct, and if there are seams, they should be sealed.
5. The connection between the steel plate air duct and the brick or concrete air duct should conform to the air flow direction, and the joint surface between the air duct and the air duct must be sealed.
6. The support and hanger of the thermal insulation duct should be set outside the thermal insulation layer, and the thermal insulation layer must not be damaged.
7. When the air supply pipe and the main pipe are connected vertically, an air guide adjustment device should be installed at the interface.
Seventh, air duct tightness test.
After the air duct is installed, the tightness inspection should be carried out according to the pressure level of the system. The air leakage volume should meet the requirements of the national standard "Code for Acceptance of Construction Quality of Ventilation and Air Conditioning Engineering" GB50243, and the tightness inspection of the system should comply with the light leakage method in Appendix A of the GB50243 specification Provisions for detection and air leakage testing. Sampling inspection should be adopted for tightness inspection of low-voltage system, the sampling inspection rate is 5% and the sampling inspection is not less than one system. When the processing technology and light leakage test are unqualified, the air leakage test shall be carried out according to the specified sampling rate. The tightness inspection of the medium-voltage system should be carried out under strict light leakage inspection conditions, and the air leakage of the system air duct should be randomly inspected. The sampling inspection rate is 20%, and the sampling inspection is not less than one system.
All high pressure systems should be tested for air leakage.
Eighth, finished product protection.
1. The surface of the installed air duct should be smooth and clean, and the outdoor air duct should be protected from rain and snow.
2. When the air duct extends into the structural air duct, steel mesh should be installed at the end to prevent debris from entering the metal air duct when the system is running. The gap between the metal air duct and the structural air duct should be sealed tightly.
3. When the air duct passes through the settlement joint, a casing should be added according to the design requirements, and the gap between the casing and the air pipe should be tightly sealed with filler (soft).
4. When transporting and installing stainless steel and aluminum air ducts, the phenomenon of scratching the surface should be avoided. During installation, contact with iron objects should be minimized.
5. When transporting and installing the valve parts, the surface and blade deformation due to collision should be avoided. Outdoor stacking should be protected from rain and snow.
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