Diagnosis of moisture temperature deviations in compressor systems: choice of refrigerant, contamination of the heat exchanger, malfunction of the discharge valve and incorrect load

1. Problem description and scope

This guide is intended for diagnosing deviations of moisture temperature (dewpoint) in compressor systems, in particular, when moisture in the air coming out of dry air increases. The problem can occur in systems using refrigerated dryers due to refrigerant balance inconsistencies, heat exchanger contamination, bypass valve failure, or improper load matching to the system. Average moisture temperature deviations can be critical for production, especially in the electronics, food and pharmaceutical industries, where high humidity can lead to product failure.

2. Preventive measures

Use personal protective equipment (PPE) and perform lockout and tagout when diagnosing compressor systems.
Turn off power and disconnect pneumatic lines before examining the system to avoid accidental cuts.
Test for residual pressure in the system before accessing components.
Use temperature and moisture measurement tools only after performing blocking and tags.

3. Necessary diagnostic tools

4. First assessment and checklist

5. Systematic diagnostic scheme

1. If the moisture temperature is outside the permissible range:
• Check the refrigerant level
• Measure the pressure in the system
• If the pressure is higher, check compliance
• If the pressure is lower, check for leaks or damage
2. If the deviation occurs from time:
• Check the cleanliness of the heat exchanger
• Measure the temperature at the inlet and outlet of the heat exchanger
• If the temperature is higher, contamination is possible
• If the temperature is lower, check for refrigerant leakage
3. If the deviation occurs after opening the valve:
• Check the operation of the valve
• Measure the pressure after the valve
• If the pressure is higher, the valve does not work
• If the pressure is lower, the valve sucks
4. If the deviation occurs when the load changes:
• Check the compatibility of the load with the system
• Measure the moisture temperature in different modes
• If the humidity is higher, the load exceeds the system's capabilities
• If the humidity is lower, the load is less

6. Matrix of deviations of causes

7. Analysis of the causes of each malfunction

7.1 Insufficient refrigerant level

Insufficient refrigerant level occurs due to leakage or incorrect dosage. This leads to a decrease in the efficiency of the dryer, an increase in moisture in the air and moisture temperature deviations. In the absence of a refrigerant, the system cannot maintain a temperature below 4°C, which leads to knocking out products.

7.2 Contamination of the heat exchanger

Contamination of the heat exchanger can occur due to the accumulation of dust, microbes or other contaminants. This leads to a decrease in the efficiency of heat exchange, an increase in the temperature at the inlet and outlet, which affects the temperature of moisture. Contamination can occur due to improper cleaning or high levels of moisture in the air.

7.3 Malfunction of the diverter valve

Failure of the drain valve leads to improper drainage of moisture or leakage of refrigerant. This can occur due to mechanical damage, suction or incorrect opening. A failure of the drain valve leads to an increase in moisture in the air and deviations in the moisture temperature.

7.4 Incorrect load

Improper loading can lead to system overload or underutilization. This can occur due to incorrect selection of components, changes in manufacturing conditions or lack of regulation. Improper loading leads to an increase in moisture in the air and deviations in moisture temperature.

8. Step-by-step repair procedure

8.1 Insufficient refrigerant level

1. Measure the refrigerant level
2. If the level is below 60%, dose the refrigerant
3. Use a refrigerant dispenser for dosing
4. Check the pressure after dosing
5. Measure the moisture temperature after dosing

8.2 Contamination of the heat exchanger

1. Measure the temperature at the inlet and outlet of the heat exchanger
2. If the difference is more than 5°C, clean the heat exchanger
3. Use a pressure washer to clean
4. Check the cleanliness of the heat exchanger after cleaning
5. Measure the moisture temperature after cleaning

8.3 Malfunction of the diverter valve

1. Measure the pressure after the valve
2. If the pressure is higher than 5 bar, replace the valve
3. Use a new valve according to specification
4. Check valve operation after replacement
5. Measure the moisture temperature after replacement

8.4 Incorrect load

1. Measure the moisture temperature in different modes
2. If the humidity is higher, reduce the load
3. Use adjusting devices to set the load
4. Check that the load is within specification
5. Measure the moisture temperature after adjustment

9. Preventive measures

10. Spare parts and components

Visit our e-catalog at https://www.unitecd.com/e-catalog/ for parts and components.

11. Links

• Certification EN 378:2010
• Certification ISO 8068:2012
• DSTU 4955:2018 certification
• Original documentation of the manufacturer
• UNITEC-D maintenance guides