Replacement of regulating compressor/four way and stop valve
Writer： admin Time：2021-03-26 21:18 Browse：℃
Replacement process of regulating compressor, four way valve and stop valve
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Compressor replacement process
1. Release refrigerant: open the high and low pressure valves with an Allen key.
Pay attention to the ventilation of the working environment to avoid suffocation;
The speed of discharging refrigerant should not be too fast to avoid personnel being frostbitten by refrigerant; at the same time, the refrigerant oil in the compressor should not be discharged with refrigerant. Once the compressor is in good condition after subsequent inspection, the lack of refrigerant oil will affect the normal use. Pay attention to the spray Color of the refrigerant. If the spray is white or colorless, the internal cleanliness of the system is higher. The compressor may not be damaged.
2. Remove the suction and exhaust pipes: confirm that the refrigerant has been exhausted;
Fill the system with nitrogen;
The flame was adjusted to neutral flame;
Preheat the welded joint with welding Qi, melt the solder at the welded joint, and then draw out the suction and exhaust pipes;
3. No load operation: the orifices of suction and discharge pipes of old compressors are open;
Note: before the old compressor is removed, ensure that the running time of the suction and discharge pipe orifice is not more than 5 seconds under the open state, and judge whether the compressor monomer is blocked and whether there is suction and discharge.
To test whether the compressor has suction and exhaust, you can feel it with your fingers close to the exhaust port;
The old compressor with poor insulation and high running current may leak electricity, so it cannot be tested by this method.
4. Remove and dispose of old compressor:
Remove the old compressor, weld the process pipe to the suction and discharge pipe of the compressor, and then clamp and seal the process pipe.
5. Cleaning system:
Spray the cleaning solution into the condenser and evaporator, then blow in high-pressure air or nitrogen, and repeat the above process for two or three times until the liquid blown out by the air is clean;
Blow high pressure air or nitrogen from the opposite direction for more than 10 seconds
Note: the cleaning solution should be highly soluble and volatile, R11 is recommended;
It is necessary to ensure the cleanness of the welding nozzle; if the compressor oil is blackened or has more impurities, it is necessary to clean the system and replace the liquid storage tank and filter.
6. Replace with a new compressor:
Place the compressor foot pad on the base plate bolt, and the upper part of the rubber foot can be lubricated with a little detergent (not oil); put in the compressor; screw the foot screw; pull out the rubber plug of the compressor exhaust pipe; pull out the rubber plug of the compressor suction pipe.
In principle, it is required to use the original brand compressor of the prototype number, but if it can not be satisfied, it must ensure that the capacity of the new compressor is consistent with that of the old compressor;
Scroll compressor and rotor compressor cannot be interchanged;
Single phase compressor and three-phase compressor cannot be interchanged;
When pulling out the rubber plug of the compressor, the exhaust pipe must be removed before the suction pipe;
The lubricating oil must not be contacted during maintenance.
7. Welding new compressor:
To ensure that the welding pipe orifice is clean and free of oil, connect the copper pipe; fill nitrogen into the copper pipe; ignite the welding, adjust the flame to neutral flame; the flame should be vertical to the welding position as far as possible, and do Z-shaped moving preheating; when the copper pipe surface is reddish Brown, fill the welding seam with solder, infiltrate into the welding seam, and withdraw after the welding seam is filled.
The welding position must be filled with nitrogen;
Preheat until the copper tube turns pink;
The welding rod must be melted by the temperature of copper tube, not by flame;
The welding quality should be full and glossy with no burr;
When welding, do not burn to the root of the suction and exhaust pipe. The terminal cover needs to be removed after the welding process, and the flame direction cannot face the terminal position;
8. Leakage detection of pipeline binding and welding. Special attention for compressor replacement: air operation is highly dangerous. When the compressor is running, if the high-pressure side is blocked by welding and the low-pressure side leaks, the mixture of inhaled air and refrigeration oil will spontaneously ignite and explode when it reaches the flash point temperature under high temperature and high pressure.
Occurrence Principle: the compressor inhales air, the exhaust side (such as capillary, four-way valve, etc.) is blocked, the air is continuously inhaled and compressed, the compressor overheats, and the refrigeration oil gasifies to form oil vapor mixture. When the temperature and pressure reach a certain condition, the oil-gas mixture will ignite and burn! Temperature and pressure rise sharply! When the pressure exceeds the compressive strength of the shell (160 ~ 200kg / cm2), the shell will burst!
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Four way valve replacement method
Before welding the four-way valve, the four-way valve must be wrapped with wet cloth, and the whole four-way valve assembly must be welded. Pay attention to the direction of flame during welding, and the flame is not allowed to heat the valve body;
Immerse the four-way valve in water for replacement (design simple and applicable tooling as far as possible). In order to control the relative angle between the pipeline parts of the four-way valve assembly, remove one pipeline part, install a new valve, and then remove and replace other pipeline parts after welding. During the replacement process, the internal parts of the new and old four-way valves should not be burnt out, and the welding quality of the new valve and the analysis effect of the old valve after returning should be ensured;
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When installing the four-way valve assembly, the four-way valve must be wrapped with wet cloth. At the same time, pay attention to the direction of flame during welding, and the flame is not allowed to heat the valve body;
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When replacing the four-way valve, because the copper pipe has been welded many times, try to use silver filler metal. If there is no silver filler metal, add flux when using copper phosphorus filler metal for welding;
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When welding four-way valve for cooling, attention should be paid to avoid water entering the valve body;
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When welding, nitrogen should be filled for protection to reduce oxide scale if possible. After welding, nitrogen should be used to blow out oxide scale inside the four-way valve if possible.
Judgment of cross flow of four-way valve in air conditioner refrigeration system
A. When the fluorine is collected by refrigeration, when the fluorine is almost collected, the return gas has no temperature (that is, normal temperature). When you touch the two low-pressure pipes of the four-way valve by hand, there is no obvious temperature difference, so the four-way valve is normal (of course, the two high-pressure pipes are very hot and need not be touched). The low -pressure inlet pipe of the four-way valve is normal temperature, and the outlet pipe (to the compressor) becomes obviously hot.
B. The cross flow four-way valve has a larger airflow sound.
C. The cross flow of the four-way valve will lead to endless fluorine collection, and the return gas pressure is about 0.1MPa or more.
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Precautions for stop valve installation or maintenance
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The bell mouth of the indoor and outdoor connecting pipe must be aligned with the thread of the stop valve joint, and the nut shall be tightened by hand. Generally, the joint thread shall be screwed in by hand, and the spanner is allowed to tighten the nut only after more than 3 threads are screwed in (some refrigerant oil can be wiped on the thread to facilitate manual tightening of the nut). If only 1-2 threads are screwed in, the joint thread must be checked to see if there is scratch or sliding;
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After the air conditioner is installed online, the valve core and valve core nut must be installed on the valve body with a certain torque;
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After the nut and joint thread are tightened manually, the wrench is used for locking. When the nut is full of all threads, the half thread is twisted back, and then the nut is tightened.
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When replacing the stop valve, before welding the stop valve, first discharge the refrigerant in the system, and then wrap the stop valve with a wet cloth. Pay attention to the direction of the flame during welding, and do not allow the flame to heat the valve body, so as not to damage the sealing ring and affect the fault cause analysis;
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When welding a new stop valve, in principle, it is required to put the stop valve into water before welding. In special cases, the method of wrapping wet cloth can be used, and welding operation without cooling is not allowed;
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There are 7 / 16 ', 5 / 8', 3 / 4 ', 7 / 8' and 17 / 16 'marks on the valve body of British screw globe valve. When matching copper nuts of connecting pipe, it is necessary to pay attention to the corresponding use of metric and British system. All copper nuts of connecting pipe with conical surface on the external surface of household air conditioner are British nuts;
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When the welding stop valve is cooled, attention should be paid to avoid water entering the valve body;
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When welding, nitrogen should be filled for protection if possible to reduce the generation of oxide scale. After welding, a small amount of refrigerant can be used to flush the oxide scale at the welding position of stop valve if possible.
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