Reasons for high temperature tripping of screw air compressor (Part 1)

1. Excessive ambient temperature has the following two impacts on screw air compressors:

A： The higher the temperature, the thinner the air (just like air compressors have low efficiency in high-altitude areas), resulting in a decrease in the efficiency of the air compressor, causing it to be in a loaded state for more time, carrying more load, and generating more heat. As a result, the temperature of the air compressor will definitely be higher.

B： When designing an air compressor, there is usually a design operating environment temperature. The maximum temperature of the air compressor operating at the design operating environment temperature is usually close to the protection temperature of the air compressor. If the ambient temperature of the air compressor is higher than the design operating environment temperature, it will increase the temperature of the air compressor, causing it to even exceed the shutdown temperature of the air compressor, resulting in high temperature of the air compressor.

2. The air compressor system is short of oil

The oil level in the oil and gas tank can be checked. After the shutdown and pressure relief, when the lubricating oil is in a static state, the oil level should be slightly higher than the high oil level mark H (or MAX). During the operation of the equipment, the oil level should not be lower than the low oil level mark L (or MIN). If insufficient fuel is found or the oil level cannot be observed, the machine should be stopped immediately to refuel.

3. The oil shut-off valve is not working properly

The oil shut-off valve is usually a two position, normally closed solenoid valve that opens when starting and closes when stopping to prevent the oil in the oil and gas tank from continuing to spray into the machine head (main engine) and from spraying out from the air inlet during shutdown. If the component is not turned on during loading, the machine head (host) will rapidly heat up due to lack of oil, and in severe cases, it may cause the screw assembly to burn out.

4. Oil filter

A: The bypass valve of the oil filter is blocked and cannot be opened, which will cause the air compressor oil to not reach the machine head (main engine), and the machine head (main engine) will quickly heat up due to lack of oil.

B: When the oil filter is clogged and the flow rate decreases, there is a situation where the air compressor's temperature gradually rises due to incomplete heat removal, resulting in high temperatures; Another situation is that after the air compressor is unloaded, the air compressor is at high temperature because the internal oil pressure of the air compressor is high during loading, and the air compressor oil can pass through. However, after the air compressor is unloaded, the oil pressure of the air compressor is low, making it difficult for the air compressor oil to pass through the air compressor oil filter. The flow rate is too small, resulting in high temperature of the air compressor.

5. Thermal control valve (temperature control valve) malfunction

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 (main engine) above the pressure dew point. Its working principle is that when it is first turned on, due to the low oil temperature, the thermal control valve branch opens and the main circuit closes, and the lubricating oil is directly sprayed into the machine head (main engine) without passing through the cooler; When the temperature rises above 40 ℃, the thermal control valve gradually closes, and oil flows through both the cooler and the branch at the same time; When the temperature rises above 80 ℃, the valve is completely closed, and all lubricating oil enters the machine head (main engine) through the cooler to cool the lubricating oil to a greater extent.

If the thermal control valve malfunctions, lubricating oil may enter the machine head (main engine) directly without passing through the cooler, causing the oil temperature to fail to decrease and leading to overheating. The main reason for its failure is that the elastic coefficient of the two thermal sensitive springs on the valve core changes after fatigue, and they cannot operate normally with temperature changes; Secondly, the valve body is worn, and the valve core is stuck or does not move properly, making it unable to close normally. It can be repaired or replaced according to the situation.

6. Check if the fuel regulator is functioning properly, and if necessary, increase the fuel injection amount appropriately

The fuel injection quantity has been adjusted before the equipment leaves the factory and should not be changed under normal circumstances.

7. Engine oil has exceeded its usage time and deteriorated

The fluidity of the engine oil deteriorates, and the heat exchange performance decreases. Causing the heat of the air compressor head (main engine) to not be completely removed, resulting in high temperature of the air compressor.

8. Check if the oil cooler is working properly

For water-cooled models, the temperature difference between the inlet and outlet water pipes can be checked. Normally, it should be between 5-8 ℃. If the temperature is below 5 ℃, scaling or blockage may occur, which will affect the heat transfer efficiency of the cooler and cause poor heat dissipation. In this case, the heat exchanger can be removed and cleaned.

9. Check if the inlet temperature of the cooling water is too high, if the water pressure and flow rate are normal. For air-cooled models, check if the ambient temperature is too high

The inlet temperature of cooling water should generally not exceed 35 ℃, the water pressure should be between 0.3-0.5MPA, and the flow rate should not be less than 90% of the specified flow rate. The ambient temperature should not exceed 40 ℃. If the above requirements cannot be met, solutions can be taken by installing cooling towers, improving indoor ventilation, and increasing the space in the computer room. You can also check if the cooling fan is working properly. If there is a malfunction, it should be repaired or replaced.

JOY MACHINERY always adheres to the corporate vision of "building a leading brand of oil-free air compressors in the world", and hopes to provide high-quality, clean and safe air for food, beverage and other production enterprises on the road of oil-free air compressor research and development, production and sales. Source protection, and also contribute a little bit to people's health and safety.

JOY MACHINERY oil-free air compressor series is widely used in the food and beverage processing industry due to its clean air source and continuous and stable gas transmission. If you have any needs, please contact us! JOY Machinery (Shanghai) Co., Ltd. has a professional design team with rich experience and welcomes customization. Diversified products can meet most applications and meet your one-stop shopping needs. The air compressor series includes power frequency screw air compressors, variable frequency screw air compressors, permanent magnet variable frequency screw air compressors, two-stage compression screw air compressors, integrated screw air compressors, laser cutting air compressors, medium and high pressure air compressors. Air compressors, oil-free water-lubricated screw air compressors (special oil-free screw air compressors for the medical industry), diesel-moving screw air compressors, electric-moving screw air compressors and other products.

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