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Common faults of safety valve and temperature control valve of screw air compressor

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Update time : 2021-05-12 13:41:28
1. The safety valve is also called the overflow valve, which plays a role of safety protection in the compressor system. When the system pressure exceeds the specified value, the safety valve opens, and part of the gas in the system is discharged into the atmosphere, so that the system pressure does not exceed the allowable value, so as to ensure that the system does not cause accidents due to excessive pressure.

The common faults of safety valves are as follows:

(1) Gas leakage or failure to start. Insufficient airtightness is mostly caused by the lack of maintenance of the compressor for a long time, and the surface of the accessories is too dirty or worn, and should be cleaned and replaced in time. Another possibility that cannot be started is that the settings are inaccurate.
 

(2) Constant vibration. The matching spring is not suitable, the stiffness is improper, and it needs to be adjusted.

 

Compressor safety valves belong to the category of automatic valves. According to the "Safety Valve Safety Technical Supervision Regulations", the regular verification of safety valves is generally at least once a year. The formal safety valve calibration methods include: offline calibration of the calibration platform, online instrument calibration, and step-up jump method verification. It can also be checked by a simple method, that is, when the compressor is working at full load, gently open the valve cover, and if the safety valve can discharge outward, it is regarded as normal. High-temperature oil mist will be brought out when the safety valve is vented outwards. Pay attention to safety.

2. The function of the temperature control valve is to control the exhaust temperature of the machine head. Its working principle is that the temperature control valve core adjusts the oil passage formed between the valve body and the housing by extending and contracting according to the principle of thermal expansion and contraction. , So as to control the proportion of lubricating oil entering the oil cooler, so as to ensure that the rotor temperature is within the set interval. 

When the exhaust temperature of the machine head is too low, moisture will precipitate in the oil and gas barrels, causing the lubricating oil to emulsify. When the cold engine starts, the temperature control valve forces the lubricating oil directly into the machine head without passing through the oil cooler. When the oil temperature rises to a certain value, the temperature control valve completely opens the passage through the oil cooler. At this time, all the lubricating oil is cooled by the oil cooler and then sprayed into the machine head.
 

Since the lubricating oil entering the temperature control valve is not filtered, the internal passage of the temperature control valve is more complicated, which is easy to cause dirt accumulation. After long-term use, the failure rate of the temperature control valve is relatively high, which often leads to high temperature protection of the machine. In addition, after the temperature control valve completely opens the passage to the oil cooler, it cannot completely cut off the passage of hot oil directly into the machine head. The temperature of the lubricating oil entering the machine head is always higher than the outlet temperature of the oil cooler, resulting in low cooling efficiency. Therefore, some manufacturers’ models do not have a temperature control valve, and control the oil temperature by controlling the start and stop of the fan motor. When the temperature of the exhaust air at the head of the machine rises to 90°C, the fan starts to run. If the temperature is lower than 70°C, The fan stops running to keep the temperature within a certain range.
 

By checking the four oil pipes connected with the temperature control valve, it can be judged whether the temperature control valve is working normally. The four oil pipes are: oil barrel to temperature control valve, temperature control valve to oil cooler, oil cooler to temperature control valve, and temperature control valve to oil filter; normal temperature is: high, high, low, slightly higher .