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Installation of refrigerant pipes and other pipelines in refrigerant system

时间:2021-11-17浏览次数:403
1、 Refrigerant system device standard
1. When positioning and setting out, the copper pipe should be straight, the branch should be reasonable, and the line should be the shortest. Multiple systems in parallel must ensure that the pipeline is straight and highly divergent.
2. Copper pipe is fixed with Ф 8. Full wire round steel hanger, hanger spacing:
When the diameter of refrigerant pipe is less than 20mm, the spacing between supports and hangers shall not be greater than 1.2m;
When the diameter of refrigerant pipe is greater than 20mm, the spacing between supports and hangers shall not be greater than 2m.
3. Welding of copper pipe
Welding should be carried out downward or sideways to prevent overhead welding as far as possible. During welding, nitrogen of about 0.05Mpa must be filled into the piping first to wash away the air in the piping.
Nitrogen shall be used for maintenance during welding to avoid oxide during welding. After welding, nitrogen can be used for cooling, and cold water cannot be used for spraying, so as to avoid sudden cracks at the welded junction.
4. Flared connection of piping
The copper pipe shall be cut with a pipe cutter as far as possible, and care shall be taken to avoid copper chips falling into the pipe.
There shall be no inclination, deformation, crack and other defects after flaring.
5. Piping flushing
During the installation and construction of piping, it is inevitable that dust and moisture will enter the pipe, so the piping must be washed after the completion of piping construction. (note that the gas used can only be nitrogen, and other gases cannot be used. For example, there is a risk of condensation with refrigerant or carbon dioxide, and there is a risk of explosion with oxygen).
6. When the refrigerant pipe is connected with the equipment, the connection port of the refrigerant pipe should be sealed to prevent moisture, dirt, dust and other impurities from entering the refrigerant pipe.
2、 Condensate system unit standard
The connection between the refrigerant pipe and the indoor unit shall be fixed at 300-500mm, the turning of the refrigerant pipe shall be fixed at 300mm, the direction of the refrigerant pipe shall be horizontal and vertical, and the support and fixation shall meet the standard.
Condensate pipe installation request
The drain pipe needs to be equipped with a vent at the highest point to ensure the smooth discharge of condensate. Condensate pipe The slope needs to be greater than 0.5%, there shall be no adverse slope.
3、 Installation standard of insulation pipe
1. The selection of thermal insulation materials must conform to the relevant technical requirements. The thermal insulation materials at the body drain must be glued to the body to avoid condensation.
4. Indoor unit standard
When the machine is hoisted, double nuts are used to fix it, so as to avoid long-term vibration of the machine and loose screws.
The hoisting screw rod shall be unified. The screw rod shall be vertical and the length shall be unified in the middle of the machine. If the length of the screw rod is greater than 1.5m, the screw rod must be reinforced with reinforcing parts to avoid bending and deformation.
The degree of indoor machine hoisting shall be within ± 1 ° to ensure the degree of later receiving and air outlet devices.
Dust prevention maintenance shall be carried out after hoisting, and the machine shall be wrapped and maintained in a timely and all-round manner after hoisting, so as to prevent the dust in the decoration process from entering the machine and accumulating on the fins, resulting in the reduction of air exchange thermal area and the reduction of air conditioning effect.
3. Outdoor unit location and device request
Foundation, support and shock absorption measures shall be taken for outdoor unit installation. The weight of outdoor units is usually very large. The foundation of the device can ensure the load-bearing requirements of the device machine, and shock absorption measures can reduce noise.
Ensure that the support load can meet the application requirements. The side air outlet machine should be effectively fixed at the upper part to avoid the side deviation of the machine.
Outdoor machine level device, and the machine level device is within ± 1 °, so as to ensure the average bearing of the foundation and the stable operation of the machine.
6、 Hoisting standard of air duct
1. The air duct shall be installed horizontally, with a diameter of less than or equal to 40cm and a spacing of more than 4m.
2. The distance between supports and hangers of spiral air duct can be extended to 5M and 3.75m; For air ducts with steel sheet flanges, the spacing between supports and hangers shall not be greater than 3m.
3. The distance between vertical devices of air duct shall not be greater than 4m, and a single straight pipe shall have at least 2 fixed points.
5. The supports and hangers should not be set at the tuyere, valve, inspection door and automatic control mechanism, and the distance from the tuyere or socket should not be less than 200mm.
6. When the length of the suspended main and main air ducts exceeds 20m, fixed points to avoid swing shall be set, and each system shall not be less than 1.
7. The screw holes of hangers shall be machined. The suspender shall be straight, and the thread shall be intact and bright. The stress of each auxiliary support and hanger behind the device shall be average without obvious deformation. The tension or contraction of adjustable vibration isolation supports and hangers used in air ducts or air conditioning equipment shall be adjusted according to the design requirements.
7、 Device standard of control system
1. Power cord
Each outdoor unit shall be controlled by a separate switch.
Each outdoor unit shall be controlled by a separate leakage switch.
The power lines of indoor and outdoor machines should be laid through steel pipes or U-PVC pipes.
The power line and the control line shall be installed separately and shall not be put through the same sleeve.
2. Transmission line
The transmission line adopts shielded double core wire CVVs or cpevs, with no polarity. The shielding net of the shielding wire is grounded at one end.
When the total length of the transmission line should be less than 500m, the line diameter is more than 1.25mm2;
The transmission line should be laid through U-PVC pipe, and the pipe diameter of the sleeve is more than dn16.
The transmission line shall be connected in series, and there shall be no joints at other parts except the wiring terminals of outdoor and indoor units.
The connection of transmission lines shall not constitute a closed circuit.
3. Remote control line
The remote control line adopts unshielded double core wire with a wire diameter of 0.5-0.75mm2;
When the length of the remote control line exceeds 10m, the cable with the same specification as the transmission line shall be used.
8、 Device of air outlet and wire controller
1. Tuyere device
The air outlet device should be clean and flat without air leakage, and the joint with the air duct or canvas should be firmly sealed. The air return device should be clean and flat, and the position should correspond to the air return position of the machine.
2. Wire controller device
The wire controller device should be clean, flat and solid to meet the height and position requirements of users.
9、 Multi online debugging standard
1. System cleaning
After all pipeline devices are completed, the pipeline shall be purged with nitrogen before connecting with the indoor unit. Ensure that the inside of the piping system is clean and free of dirt.
2. Condensate system water test
After the completion of pipe connection, water test and full water test shall be carried out. On the one hand, check whether the drainage is smooth and whether it leaks. Test the water from the highest point of the system to see whether the drainage is smooth and whether the water volume is normal.
3. Pressure test of refrigerant system
When leaving the factory, the stop valve of the outdoor unit has been closed, and it should be confirmed when installing.
Before the experiment, a small amount of oil should be applied to the nano cap and tube, and two wrenches should be used to fix the nano cap. The experimental pressure of the system is 4.15mpa. The pressure test is divided into three steps, and the pressure is increased slowly:
Boost the pressure to 0.5MPa (5kg/cm2) first, and stop the pressurization for more than 5 minutes for leakage inspection;
Increase the pressure to 1.5MPa (15kg/cm2), stop the pressure for 5 minutes and check the air tightness;
Then boost the pressure to 4.15mpa (42kg/cm2), conduct strength test, and hold the pressure for more than 24 hours. If the pressure does not drop, it is qualified.
Note:
Pressure correction: when the temperature changes by 1 degree, the pressure changes by 0.1kg/cm2.
At the same time, fill nitrogen from the gas pipe and liquid pipe. The range of the pressure gauge is 6.0MPa.
If it is necessary to maintain the pressure for a long time, the pressure should be reduced to less than 3.5Mpa.
10. Refrigerant addition
The refrigerant filling volume of the multi online system includes three parts: the refrigerant that has been filled before the outdoor unit leaves the factory, the refrigerant that needs to be filled by the indoor unit, and the refrigerant that needs to be filled in the connecting indoor and outdoor pipelines.
Before adding refrigerant, the refrigerant pipe must be purged and air tight. After passing the air tightness test, the air in the refrigerant pipe must be evacuated with a vacuum pump. When using a vacuum pump to vacuum, first, to avoid the smooth oil of the vacuum pump flowing back into the refrigerant pipe, a vacuum pump with an electronic one-way valve can be used. Second, to press down both sides of the refrigerant pipe and evacuate at the same time. It is qualified to adhere to the vacuum for 1h after evacuation, and then add refrigerant. Add refrigerant according to the diameter and length of refrigerant pipe, and then add it quantitatively with electronic scale. Too much or too little refrigerant will affect the cooling and heating effect of indoor units.
6. Summary
The multi on-line system device is a set of meticulous work. Under the condition that there is no corresponding device quality specification in the country and the designer does not understand the guidance and requirements of construction quality, most of the construction is based on the manufacturer and experience of guiding devices. After the completion of the project, there are many problems in the system operation, such as poor heating (cooling) effect of indoor air conditioning, lack of refrigerant dose, outdoor unit without air duct, etc. With the help of the experience of this project, we can pay attention to the construction of other projects.

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