Guide for Diagnosing High Exhaust Temperature in Screw Compressor

1. Problem Description and Scope

This guide is intended for the diagnosis and correction of high discharge temperature in a screw compressor. The problem may occur in various types of industrial equipment, including compressor units, cooling systems and production complexes. According to the severity category, high discharge temperature is considered a critical issue, as it may lead to compressor damage, reduced service life or even explosion.

2. Safety precautions

Turn off the compressor power supply and perform locking and tagging before carrying out any diagnostic procedures.
Use personal protective equipment (insulation, gloves, goggles).
Check for any stored energy sections, such as compressor units, which may accidentally start.

3. Required diagnostic tools

4. Check before starting diagnostics

5. Systematic Diagnostic Flow

1. Symptom: Exhaust temperature > 90°C
   1. Check oil level
      1. If oil level is below normal — increased exhaust temperature due to insufficient cooling effect
   2. Check the condition of the cooling calorifier
      1. If the calorifier is contaminated — obstruction to cooling due to accumulation of waste
   3. Check the thermostat operation
      1. If the thermostat is not working — incorrect temperature regulation
   4. Check the ambient temperature
      1. If the ambient temperature is higher than 30°C — influence of the external environment on the exhaust temperature

6. Failure Cause Matrix

7. Diagnosis of Fault Causes

7.1. Insufficient oil level

Causes: Low oil level may be due to leakage, evaporation or lack of regular inspection. If the oil level is below 50%, this leads to loss of cooling efficiency.

Diagnosis: Use a ruler to measure the oil level. If the level is below 50%, perform additional actions.

Effect: Without oil, the compressor cannot cool effectively, leading to overheating.

7.2. Contaminated Cooling Air Heater

Causes: Contamination of the heater may be due to debris, dust or chemical substances. If the heater is contaminated, it cannot effectively cool.

Diagnosis: Use thermography to determine temperature profiles. If the heater is higher than 80°C, it is contaminated.

Effect: A contaminated heater causes loss of cooling efficiency, leading to overheating.

7.3. The thermostat is not working

Causes: The thermostat may fail due to lack of regular inspection or mechanical damage. If the thermostat is not working, it cannot regulate the temperature.

Diagnosis: Use a multimeter to measure electrical parameters. If the thermostat does not meet the standards, it does not work.

Effect: A non-operational thermostat causes incorrect temperature regulation, leading to overheating.

7.4. High Ambient Temperature

Causes: High ambient temperature may be due to external conditions. If the ambient temperature is higher than 30°C, it affects the exhaust temperature.

Diagnosis: Measure the ambient temperature. If it is higher than 30°C, it affects the exhaust temperature.

Effect: High ambient temperature causes loss of cooling efficiency, leading to overheating.

8. Step-by-step correction procedures

8.1. Insufficient oil level

1. Check the oil level.
2. If the level is below 50%, add oil to the normal level.
3. Check for leakage.
4. If a leak is detected, perform the repair.
5. Check the exhaust temperature after adding oil.

8.2. Contaminated Cooling Air Heater

1. Check the condition of the cooling calorifier.
2. If the heater is contaminated, clean it.
3. Use thermography for temperature checking.
4. If the temperature of the heater is higher than 80°C, clean it.
5. Check the exhaust temperature after cleaning.

8.3. The thermostat is not working

1. Check the thermostat.
2. If the thermostat is not working, replace it.
3. Use a multimeter to check electrical parameters.
4. If the thermostat does not meet the standards, replace it.
5. Check the exhaust temperature after replacement.

8.4. High Ambient Temperature

1. Check the ambient temperature.
2. If the temperature is higher than 30°C, use cooling systems.
3. Check the ventilation in the room.
4. If ventilation does not meet the standards, perform repair.
5. Check the exhaust temperature after correction.

9. Preventive Maintenance Network

10. Parts and Components

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11. References

• DSTU 3011-99 - State Standards for Industrial Equipment
• EN 12952 - Standards for compressors
• ISO 1219 - Standards for Screw Compressors
• CE - Certificate of Conformity
• UkrSEPRO - Ukraine Conformity Certificate
• UNITEC-D Technical Guides - Additional Materials for Diagnostics