Relevant valves and equipments in refrigeration equipment system are in proper state. Compressor suction and exhaust valves, oil separator inlet and outlet valves, condenser and reservoir inlet and outlet valves are all in correct opening position; throttle valves are properly opened; fans and motors are running smoothly; pumps in water circulation system are running normally without abnormal sound; water circulation pipelines and their connections are not serious. Water leakage phenomena; in the cold storage with cooling exhaust pipes or cold storage fan, the exhaust pipes or cold fan coils are evenly covered with "dry frost"; the joints of Freon refrigeration system should not leak oil (oil leakage indicates refrigerant leakage), and there should be no obvious leakage of ammonia in the valves and joints of ammonia system.

1. Condensation pressure corresponds to condensation temperature, evaporation pressure and evaporation temperature. Evaporation temperature and pressure depend on the required refrigeration temperature. Evaporation pressure should be similar to the suction pressure of compressor in operation. The condensation temperature and pressure depend on the temperature and flow of the cooling medium. Generally, for refrigeration compressors of national standard series, the condensation pressure of R22 and R717 is not more than 1.8 MPa (gauge pressure). In operation, the condensation pressure is close to the exhaust pressure of the compressor and the pressure of the liquid reservoir, but it is abnormal if it is not close.

2. The water pressure of cooling water in horizontal shell-and-tube condenser should be above 0.12MPa, and a certain intake temperature and water volume must be guaranteed, while the air-cooled condenser should maintain a certain intake temperature, air volume and wind speed on the windward side. When touching the shell of horizontal shell-and-tube condenser by hand, the upper part should be hot and the lower part should be cool. The temperature difference between the inlet and outlet water of vertical condenser is in the range of 2-4 C, and that of horizontal condenser is in the range of 4-6 C.

3. The liquid level of refrigerant in the reservoir meets the requirements. The liquid level of the reservoir should be between 1/3 and 2/3 of the liquid level indicator in normal operation.

4. The automatic return tubing of oil separator with automatic return oil should be hot and cold at the right time, and the general period of cold and hot is about 1 hour. The operation of filters and solenoid valve coils on the liquid pipeline of refrigeration system should be warm and hot. There should be no obvious temperature difference between the front and back of the coils, and frost and dew should not occur. Otherwise, the coils would be blocked.

5. Throttle valve body frost or dew uniform, the entrance can not appear thick frost. When the refrigerant liquid passes through the throttle valve, only a dull little noise can be heard.

6. Protection devices on refrigeration equipment, such as safety valves and bypass valves, should be flexible in opening and closing, and the setting values of various control devices, such as pressure controller, differential pressure controller and temperature controller, should be correct and operate normally. Pressure gauge pointer should be relatively stable and flexible.