Screw Compressor Exhaust Temperature Too High: Causes and Fixes

In compressed-air systems, maintaining optimal operating conditions is crucial for efficiency and longevity. One common issue that can significantly impact performance is a high exhaust temperature from the screw compressor. This problem can arise from various causes, each requiring a specific approach to resolve.

Cooler Fouling

High exhaust temperatures can often be attributed to cooler fouling, which restricts the flow of air through the cooler. This fouling can be caused by dust, dirt, or other contaminants that accumulate over time. To diagnose cooler fouling, check for the following:

• Reduced airflow through the cooler
• Dirty or clogged air filters
• Decreased cooling efficiency

To address cooler fouling, ensure regular cleaning and maintenance of the cooler and air filters. Cleaning can typically be done using compressed air to blow out loose dirt and debris. In more severe cases, disassembly and thorough cleaning may be necessary.

Ambient Temperature

The ambient temperature around the compressor can also affect the exhaust temperature. Higher ambient temperatures can lead to increased heat in the compressed air, which can then cause the exhaust temperature to rise. To mitigate this issue, consider the following:

• Ensure proper ventilation around the compressor
• Position the compressor in a cooler area of the plant
• Use shading or cooling systems to reduce the ambient temperature

Oil Level and Type

The oil level and type used in the screw compressor can significantly impact the exhaust temperature. Using the wrong type of oil or having an incorrect oil level can lead to poor heat transfer and increased exhaust temperatures. To address this issue, ensure the following:

• Use the recommended oil type as specified by the manufacturer
• Maintain the correct oil level as per the manufacturer’s guidelines
• Regularly check and top up the oil as needed

Thermostatic Valve

The thermostatic valve in the screw compressor is responsible for regulating the oil temperature by directing oil through the cooler. If the valve is malfunctioning, it can cause the exhaust temperature to rise. To diagnose and fix issues with the thermostatic valve, consider the following:

• Check for any visible damage or wear on the valve
• Ensure the valve is properly seated and functioning
• Replace the valve if it is found to be faulty

Fan Issues

The fan in the screw compressor is responsible for moving air through the cooler and dissipating heat. If the fan is not functioning correctly, it can cause the exhaust temperature to rise. To diagnose and fix fan issues, check for the following:

• Ensure the fan is clean and free of obstructions
• Check for any visible damage or wear on the fan blades
• Verify that the fan is receiving the correct electrical input

Load Conditions

The load conditions on the screw compressor can also affect the exhaust temperature. If the compressor is operating at a high load, it will generate more heat, which can cause the exhaust temperature to rise. To address load conditions, consider the following:

• Ensure the compressor is not overloaded
• Optimise the system to reduce unnecessary load
• Use variable speed drives (VSDs) to match the compressor capacity to the demand

Typical Temperature Limits

It is important to understand the typical temperature limits for screw compressors. The exhaust temperature should typically not exceed 100°C (212°F) for most screw compressors. If the temperature exceeds this limit, it can indicate a problem that needs to be addressed. Regular monitoring of the exhaust temperature can help identify potential issues before they become critical.

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