The system must be evacuated after the air tightness test. The refrigerant pipeline should be pumped out twice. When the Beijing chiller is first pumped out, the compressor stop valve seems to be kept closed during the air-tightness test process; then open the compressor stop valve and the entire system including the compressor is again Vacuum. Excess refrigerant can be added between the two vacuuming to absorb the water that can exist in the pipeline. Initiate simultaneous pumping of vacuum from the low-pressure and high-pressure ends of the system, and the vacuum gauge should only leave the suction port of the vacuum pump. It is not allowed to use a compressor to vacuum by itself. Because the lubricating oil can be contaminated by the water that can exist in the system, and the vacuum degree can not reach the requirement. Sufficient inner diameter should be selected for the vacuum connection pipeline, it should be short and there should be no sharp tortuous or narrow places. The vacuum operation should be careful and precise, otherwise the air in the system will carbonize the lubricating oil under high-temperature exhaust and affect the lubricating quality. The moisture in the air can corrode metals, analyze smooth oil and form acidic substances. This situation in Beijing chillers will accelerate the formation under high exhaust pressure/temperature.
　　 Refrigerant filling should be done immediately after the system is evacuated. Initiate from the industrial interface of the night tank to stop the valve or add an additional amount of refrigerant through the filling valve. At this time, the refrigerant on the scale should keep the outlet valve down, and a dry filter should be installed on the filling pipe. If the refrigerant is not charged to an extra amount, gaseous refrigerant can be added from the low pressure side when the system is running.
　　Pay attention to events:
　　 The compressor is not allowed to start under vacuum to prevent damage to its built-in motor.
　　 It is not allowed to perform high-voltage test and electrical insulation test on the compressor under vacuum form.
　　 It is not allowed to indirectly fill liquid refrigerant from the suction side of the compressor.
　　 It is not allowed to use gas lamps or welding tools to indirectly heat the refrigerant bottle.