The high temperature of the air compressor is one of the more common faults in the use of the air compressor. In this paper, various potential causes are found and analyzed for this problem.
1. The two factors that cause the high temperature of the air compressor
A: When the temperature goes higher, the air turns thinner(just like the low efficiency of the air compressor in the plateau area), resulting in a decrease in the working efficiency of the air compressor, so that the air compressor is staying a loading state for longer time, more heat would be generate with more loading, so the temperature of the air compressor goes higher.
B: Generally, the operating ambient temperature set for the air compressor is 30-40 degrees, the general maximum temperature of the air compressor operating at the designed operating ambient temperature is close to the protection temperature of the air compressor. If the ambient temperature of the air compressor is higher than the designed operating ambient temperature, it would increase the temperature of the air compressor, so that the air compressor will even exceed the shutdown temperature of the air compressor, resulting in a high temperature of the air compressor.
2. The air compressor system is short of oil
The oil level of the oil and gas drum should be checked. After the shutdown and pressure relief, the oil level should be slightly higher than the high oil level mark H (or MAX) when the lubricating oil is static. During the operation of the equipment, the oil level cannot be lower than the low oil level mark L (or MIX). If it is found that the amount of oil is insufficient or the oil level cannot be observed, stop immediately to refuel.
3. The oil stop valve (oil cut valve) is not working properly
The oil stop valve is generally a two-position, two normally closed solenoid valve, which is opened when starting and closed when stopping, so as to prevent the oil in the oil and gas barrel from continuing to be sprayed into the machine head and ejected from the air inlet when the machine is stopped. If the element is not turned on when loaded, the main engine will heat up rapidly due to lack of oil, and in severe cases, the screw assembly will be burned.
4. Problem of oil filter
A: If the bypass valve is blocked by the oil filter and the bypass valve is not opened, the air compressor oil cannot reach the machine head, and the main engine will heat up rapidly due to lacking of oil.
B: The oil filter is blocked and the flow rate becomes smaller. In one case, the heat of the air compressor is not completely taken away. The temperature of the air compressor gradually rises to a high position. Another situation is that the air compressor is still in high temperature after the air compressor is unloaded. Because the internal oil pressure of the air compressor is high during loading, the air compressor oil can pass through, but after the air compressor is unloaded, the air compressor oil pressure is low, and it is difficult for the air compressor oil to pass through the filter. This would cause high temperature.
5. The thermal control valve (temperature control valve) fails to work
The thermal control valve is installed in front of the oil cooler, and its function is to maintain the exhaust temperature of the machine head above the pressure dew point. Its working principle is that when the oil temperature is low, the thermal control valve branch is opened, the main circuit is closed, and the lubricating oil is directly sprayed into the machine head without the cooler; when the temperature rises above 40 °C, the thermal control valve is gradually closed. The oil flows through the cooler and the branch at the same time; when the temperature rises above 80°C, the valve is completely closed, and the lubricating oil is all passed through the cooler and then enters the machine head to cool the lubricating oil to the greatest extent.
If the thermal control valve fails to work, the lubricating oil may enter the machine head directly without the cooler, so that the oil temperature cannot be lowered, resulting in over-temperature. The main reason for its failure is that the elastic coefficient of the two thermal springs on the spool changes after fatigue, and cannot operate normally with temperature changes; the second is that the valve body is worn, the spool is stuck or the action is not in place and cannot be closed normally. . It should be repaired or replaced according to the situation.
6. Check whether the oil volume regulator is working normally.
The fuel injection volume can be appropriately increased when it's necessary.
(The amount of fuel injection has been set when the equipment leaves the factory, and it should not be changed under normal circumstances.)
7.The oil exceeds the service time, and it deteriorates.
The fluidity of the oil becomes poor, and the heat exchange performance decreases when it's not changed after it's service life. The heat of the air compress or head cannot be completely taken away, resulting in high temperature of the air compressor.
8.Check if the cooler is working properly
For water-cooled models, you can check the temperature difference between the inlet and outlet water pipes. Under normal circumstances, it should be between 5 and 8 °C. Below 5 °C, there may be scaling or clogging, which will affect the heat exchange efficiency of the cooler and cause heat dissipation. If it is not good, the heat exchanger should be removed and cleaned.
If it is a water-cooled machine, check whether the cooling water inlet temperature is too high, and whether the water pressure and flow are normal. For air-cooled models, check whether the ambient temperature is too high.
The inlet temperature of cooling water should generally not exceed 35℃, and the flow rate should not be less than 90% of the specified flow rate when the water pressure is between 0.3 and 0.5MPA. The ambient temperature should not be higher than 40℃. If the above requirements are not met, it can be solved by installing cooling towers, improving indoor ventilation, and increasing the space of the working room. Also check that the cooling fan is working properly. If there is any fault, it should be repaired or replaced.
The air-cooled unit mainly checks whether the difference between the inlet and outlet oil temperature is about 10 degrees. If it is less than this value, check whether the fins on the surface of the radiator are dirty and blocked. If it is dirty or blocked, you should use clean air to blow away the dust and make it clean, and check if there is any corrosion.
9. Incorrect specifications or poor quality of lubricating oil
The lubricating oil of the screw machine generally has strict requirements and cannot be replaced at will. The requirements in the equipment instruction manual shall prevail.
10.Check if the air filter is clogged
The blockage of the air filter will cause the air compressor to be overloaded, and it will be in a loaded state for a long time, which will cause high temperature. It can be checked or replaced according to the alarm signal of the differential pressure switch. Generally, the first problem caused by the blockage of the air filter is the reduction of gas production, and the high temperature of the air compressor is a secondary manifestation.
11.Check if the pressure is too high
The system pressure is generally set at the factory. If it is necessary to adjust, the rated gas production pressure marked on the equipment nameplate shall prevail. If adjusting is too high, the overheating phenomenon will occur due to the increase in the load of the machine. This is also the same as the previous reason. The high temperature of the air compressor is a secondary manifestation. The main manifestation is that the current of the air compressor motor increases and the air compressor is shut down for protection.
12.Oil and gas separator clogged
The blockage of the oil and gas separator will cause the internal pressure to be too high, and the high pressure will cause many problems, and overheat is one of them. This is also the same as the first two reasons. The blockage of the oil and gas separator is mainly manifested by high internal pressure.
In high temperature season like summer, in order to ensure the smooth operation of your air compressor and smooth production, please maintain the air compressor regularly
