Refrigerant filling method:
1. Observe the bubbles in the sight glass.
If bubbles are observed, it means that there is a lack of refrigerant, but there is another reason that can cause bubbles, which is the pressure loss of the liquid pipe. If the pressure loss of the liquid pipe is large, the liquid refrigerant will flash into gas, and the gas will reduce the flow rate of the refrigerant when it flows through the expansion valve, and then corrode the expansion valve; if the subcooling degree of the system is small, the pressure loss will be very large. It is easy to produce bubbles seen in the sight glass. If there is no liquid but only steam, it will also appear transparent in the sight glass.
If professional personnel and experienced people observe, they will find that when the system is filled correctly, bubbles or flashes can also be seen in the sight glass. This is due to the resistance pressure drop in the liquid line in front of the sight glass, which causes the refrigerant to flash. If the fan speed is suddenly changed in cold storage, it is easy to change the condensation temperature. At this time, the temperature of the liquid in the liquid reservoir will be higher than the saturation temperature corresponding to the changed condensing pressure. At this time, evaporation will occur, and the liquid temperature will not return to normal until the temperature drops below the saturation temperature again.
2. Measure the high and low pressure of the refrigeration system.
This method is method that is often used. However, it should be noted that if the condensing air volume and evaporation air volume are insufficient, the test pressure will be affected. If the condensing air volume is inadequate, the high pressure will be high, and if the evaporation air volume of the expansion valve system is inadequate, the low pressure will be very low. Therefore, before measuring the pressure of the air conditioning system, it is necessary to ensure that the evaporative air volume in the condensing air volume is sufficient. These directly affect the judgment of the refrigerant charge.
3. Measure the compressor current.
This charging method is also cost-effective, but the test current will be different in different situations, such as the current being affected by the voltage value of the main power supply, the deviation of the voltage value causing the current deviation, and the refrigerant being charged too much. cause current changes, etc.
Sometimes there will be frost on the suction pipe. If the air volume of the evaporator is average, the refrigerant will flow through the evaporator according to the load change to prevent the suction pipe from frosting; if the load decreases, the liquid refrigerant will flow through the evaporator and enter the suction pipe. The water vapor in the surrounding air will condense on the tube, causing frost on the suction tube.
4. Weigh the charge.
This method works with any refrigeration system. This method is to weigh the injected refrigerant and find out the amount or range of the refrigerant that needs to be charged by consulting the information and related methods and must be strict when charging refrigerant r410. Because this will affect the energy saving rate and effect of the system.
This method is also a very correct observation method. As long as the manufacturer has marked the charging volume of the water cooler and the split body on the nameplate, it can be filled with weighing equipment after the system is completely dry and evacuated.