[China Refrigeration Network] The switching operation of various valves is the main work in the operation of the refrigeration system. The function of the valve is to control and guide the flow and direction of refrigerant in the system, and to cut off and conduct the connection between equipment and equipment or between equipment and the outside world. Improper operation of the valve may cause unsafe factors or accidents, so the operation of the valve must strictly abide by the operation procedures to avoid accidents. Cold storage valves mainly include stop valves, expansion valves and safety valves according to their applications. Cut-off valves are available in the form of straight-through valves and angle valves. The following work shall be done for safe operation of the valve:
1) The operator must identify the object when operating the valve, and do not open other valves by mistake and cause human accidents.
2) When opening the suction valve of the compressor, the liquid outlet valve of the condenser or the liquid reservoir, it must be carried out slowly, and sometimes it should be opened and stopped alternately, so as to avoid the wet stroke accident of the compressor caused by too fast opening speed.
3) During the opening process of each valve, especially when approaching the maximum opening degree, the handwheel must be pulled slowly, and the force cannot be too large, so as not to cause the valve core to be stuck by the valve body and the valve plate to fall off. When the valve is at the maximum opening (limited to the handwheel cannot be turned), turn the handwheel once or twice.
4) Operators shall pay attention to proper force during the closing process of each valve, and shall not use too much force to avoid damaging the valve.
5) For pipelines and equipment with liquid refrigerant, it is strictly prohibited to close the valves at both ends at the same time, so as to avoid ammonia leakage accident caused by pipeline or equipment bursting due to volume de-expansion of liquid caused by absorption of external heat. In general, most liquid explosions crack at the valve. The correct method to prevent liquid explosion is to evacuate the liquid in the liquid pipe before closing the valve of the pipe. Under special circumstances, when the liquid pipe cannot be evacuated, only the valve at one end of the liquid pipe should be closed so that the valve connecting the other end with the equipment is in an open state. If the compressor stops running completely, the liquid supply valve of the liquid reservoir should be closed first, and the total liquid supply valve of the regulating station should be closed after the system and liquid pipe are evacuated.
In the refrigeration system, special attention should be paid to the parts where liquid explosion may occur. These parts include: liquid pipeline between condenser and liquid reservoir, pipeline between high-pressure liquid reservoir and expansion valve, liquid pipeline with cut-off valves at both ends, liquid level gauge of high-pressure equipment, liquid balance pipe between ammonia containers, liquid distribution station, pipeline from outlet valve of circulating liquid reservoir to double suction end of ammonia, liquid supply pipeline of ammonia pump, pipeline between liquid reservoir and emergency ammonia drain, and all pipelines that may cause liquid explosion.
6) For valves that have not been opened and closed for a long time, the flexibility of opening and closing shall be checked regularly.
7) The safety valve in the refrigeration system must be calibrated once a year, and the safety net in question should be repaired or replaced in time.
8) Red and yellow opening and closing plates made of colored steel plates shall be hung on the handwheel of the valve to avoid misoperation as much as possible.