Maintenance solutions for refrigeration system of constant temperature and humidity test chamber

Maintenance solutions for refrigeration system of constant temperature and humidity test chamber

In the maintenance practice of the constant temperature and humidity test chamber, once the capillary tube is blocked in the refrigeration system, the evaporator and the condenser tube and the connecting pipe are broken or welded, resulting in refrigerant leakage, and the compressor is replaced, the system needs to be vacuumed. . The "self-evacuation method" is very practical in actual maintenance (especially when on-site maintenance), but its operation skills are very strong and there are certain difficulties in operation. Today, the editor of okmarts.com analyzes the problems encountered during the maintenance of the constant temperature and humidity test chamber, I hope it will be useful to everyone!

1. Prepare tools and materials: 1 multimeter, 1 test pencil, 1 set of combination screwdriver, 1 needle-nose pliers, 1 vacuum pressure gauge, 1 B-12 cylinder, about 500g refrigerant, 3 liquid filling pipes , 1 set of welding tools, several copper pipes for continuous connection.

　　2. Treatment process pipe: first cut the pipe wall about 2/3 thickness with a pipe cutter at about romm away from the sealing port of the compressor repair process pipe, and sand around the cut with a small amount of sandpaper to make the surface clean and ready for welding. Then use needle-nose pliers to clamp the end of the seal for about 10~, slowly operate to make small cracks in the copper tube at the cut, and let the refrigerant slowly leak out in a gas state (to prevent the outflow of refrigerating oil and cause the system to run out of oil), and finally seal the seal Remove all the ends. Extend one end of a copper pipe with a diameter of 6mm, a wall thickness of 0.5mm, and a length of about 150~ into a shape with an inner diameter of 6.1~ and a depth of 6mm. After connecting the nut, the other end is processed into a bell mouth to repair it with the compressor Tube welding.

　　 3. In-situ welding according to the system structure: When the main components of the constant temperature and humidity test chamber and other refrigeration accessories are repaired and replaced, they are welded in-situ according to the system structure. After the refrigeration system is overhauled (especially the compressor motor winding is burned out), a new filter drier should be replaced, otherwise the capillary tube will be blocked after a period of operation, which will affect the cooling effect. The specific replacement method is as follows: Melt down the A end of the filter drier, cut off the B end and seal the capillary port connected to the B end, take a new filter drier, and place the A end and the condenser outlet end in place After welding, the B terminal will not be welded temporarily. During operation, end A is higher than end B, which helps to improve the cooling effect. Connect refrigerant bottle valve, vacuum pressure gauge and connecting pipe.

　　4. Power on the compressor and observe: During operation, the following requirements should be met: (l) The B-end of the filter drier should be exhausted normally; (2) The pressure indication of the vacuum pressure gauge should be significantly reduced, and it is in a vacuum state. If there is no such reaction, stop the machine immediately and check whether the pipeline, gas cylinder, and pressure gauge are not properly connected, causing the intake pressure gauge to not be in a vacuum state, or blocking due to poor welding. After the cause is clear and the fault is eliminated, the power can be observed. Using this "self-evacuating method" to exhaust by the compressor can only remove most of the air in the capillary tube, evaporator, suction pipe, and compressor in the system, and it is impossible to achieve the purpose of high vacuum in the system. The self-vacuuming work should be completed within a few minutes.

5. System exhaust: The compressor is energized, and the refrigerant bottle valve is opened a little, so that the suction pressure of the vacuum pressure gauge is maintained at 0.1MPa for about 10 seconds. The gaseous refrigerant is sucked by the compressor. After passing through the condenser, The B end of the filter drier is discharged out of the system, thereby squeezing out most of the air in the compressor's high-pressure exhaust pipe, condenser pipe, and filter, and then the compressor is powered off and stops rotating. Press the B end of the filter for approximately For about 50 seconds, when the gas is ejected from end B, close the refrigerant bottle valve, and then release your finger. In this way, the entire refrigeration system is filled with refrigerant, thereby substantially exhausting air.