Guide to Correcting Moisture Temperature Deviation in Compressor Air Supply: Refrigerant Leak, Heat Exchanger Contamination, Drain Valve Failure and Load Compliance

1. Problem Description and Application Range

This guide is intended for determining the causes of dewpoint temperature deviation in compressor systems with moisture getters. It covers the operation of products in such fields as automotive manufacturing, aerospace engineering, food industry, chemical industry, and energy. The problem is classified as critical, since dewpoint temperature deviation may lead to equipment damage, product quality loss, and minor risk for workers.

2. Safety Precautions

Use personal protective equipment: respiratory protection, gloves, goggles, protective suit. Perform lockout/tagout procedure: ensure electrical power and compressor equipment are disconnected before diagnostics. Disconnect stored energy: before accessing equipment, turn off all energy sources and perform the appropriate lockout/tagout procedures. Avoid working in hazardous conditions: do not perform diagnostics under pressure or at high temperatures.

3. Required diagnostic tools

4. First assessment: check-list

5. Systematic Diagnosis: Decision Tree

1. Symptom: Humidity temperature deviation above –40°C.
   1. Check: Humidity temperature at the desiccator outlet.
      1. Result: Humidity temperature above –40°C.
         1. Possible Cause: Insufficient refrigerant charge.
            1. Diagnostic Test: Measure the temperature at the inlet and outlet of the heat exchanger.
               1. Expected Result: Temperature difference at the outlet greater than 5°C.
         2. Possible cause: Heat exchanger contamination.
            1. Diagnostic test: Measure the temperature of the heat exchanger surfaces.
               1. Expected result: Surface temperature above 60°C.
         3. Possible cause: Incorrect operation of the drain valve.
            1. Diagnostic test: Measure the current in the valve actuator.
               1. Expected result: Current less than 10 mA.
         4. Possible cause: Incorrect load matching.
            1. Diagnostic test: Measure the system pressure.
               1. Expected result: Pressure higher than 10 bar.

6. Cause and Symptom Matrix

7. Analysis of Main Causes

7.1. Insufficient refrigerant charge

Insufficient refrigerant charge causes insufficient condensation of moisture, resulting in a moisture temperature deviation. This may occur due to refrigerant leakage, incorrect system settings or component damage. To confirm, measure the temperature at the inlet and outlet of the heat exchanger. If the deviation at the outlet exceeds 5°C, this confirms insufficient refrigerant charge.

7.2. Contamination of the heat exchanger

Contamination of the heat exchanger leads to a reduction in heat transfer efficiency, causing deviations in humidity temperature. Causes may be dust, condensate or moisture. To confirm, measure the temperature of the heat exchanger surfaces. If it exceeds 60°C, this confirms contamination.

7.3. Incorrect operation of the drain valve

Incorrect operation of the drain valve leads to accumulation of moisture in the system. The cause may be leakage current in the valve actuator or mechanical damage. To confirm, measure the current in the valve actuator. If the current is less than 10 mA, this confirms malfunction of the valve.

7.4. Incorrect Load Matching

Incorrect load matching leads to an increase in system pressure, which may affect the efficiency of the desiccant. To confirm, measure the system pressure. If the pressure is higher than 10 bar, this confirms a deviation from the load.

8. Step-by-step correction procedures

8.1. Insufficient refrigerant charge

1. Measure the temperature at the inlet and outlet of the heat exchanger.
2. Check for refrigerant leakage by visual inspection or pressure measurement.
3. Add the required amount of refrigerant to the system.
4. Measure the temperature at the inlet and outlet of the heat exchanger again.
5. Check whether the temperature of humidity is within –40°C.

8.2. Contamination of the heat exchanger

1. Measure the temperature of the heat exchanger surfaces.
2. Check for contamination on the surface of the heat exchanger.
3. Clean the heat exchanger using a special cleaner.
4. Measure the temperature of the heat exchanger surfaces again.
5. Check whether the temperature of humidity is within –40°C.

8.3. Incorrect Operation of the Drain Valve

1. Measure the current in the valve actuator.
2. Check for mechanical damage to the valve.
3. Replace the valve if it is not working.
4. Measure the current in the valve actuator again.
5. Check whether the temperature of humidity is within –40°C.

8.4. Incorrect Load Matching

1. Measure the pressure in the system.
2. Check for deviation from design parameters.
3. Adjust the pressure to the design values.
4. Measure the pressure in the system again.
5. Check whether the temperature of humidity is within –40°C.

9. Preventive Measures

10. Replacement Parts and Components

Go to the UNITEC-D catalog

11. References

• CE Certification, UkrSEPRO
• DSTU 25.2-07:2016 – Equipment for Production
• EN 13737-1:2002 – Compressors and Components
• ISO 8068:2016 – Requirements for Humidifiers
• UNITEC-D Technical Training Materials