Common faults of refrigeration dryers

(1) Refrigeration system failure

1. The expansion valve is blocked

a. Symptoms: no flow observed by sight glass, ice and frost at the outlet of expansion valve, hot high pressure pipe or high pressure tripping.

b. Causes: Dirty blockage, ice blockage, thermal capillary breakage

c. Processing steps:

Adjust the superheat degree of the expansion valve;

Increase the superheat of the temperature sensor and increase the Ps pressure;

Increase the high pressure pressure (setting value of the fan pressure switch), close the hot gas bypass valve (hand valve), and perform impact and dirt blocking.

2. Clogged filter drier

a. Symptoms: The temperature difference between the inlet and outlet of the drier is large, or the outlet of the filter is frosted.

b. Processing step: replace filter drier

※Note: When the system is blocked and the equipment is running at no load, the high and low pressure values may be within the normal value range; when the load is running, the high pressure is seriously high, and even the high pressure trips. During long-term operation, a large amount of high-temperature and high-pressure gas is throttled from the hot gas bypass valve (hand valve) and directly returned to the low-pressure return gas pipe, which will then cause the compressor to become hot, the temperature of the high-pressure return gas pipe will increase to Baidu, and even cause the motor to burn out. When the compressor is overheated, the internal thermal protection of the compressor starts to work; it can be restarted only after the compressor temperature cools down naturally.

3. Compressor failure

a. Causes: motor burnout, liquid shock, and other mechanical failures;

b. Processing steps:

Measure the resistance of the motor to determine;

Three-phase motor; ROA=ROB=ROC

Two-phase motor; ROA=ROB+ROC (ROB=ROA+ROC) (ROC=ROA+ROB)

Check the condition of the capacitor equipped with the compressor;

Capacitance detection method: adjust the gear of the multimeter to the maximum range (above 200MΩ), and connect the two probes to both ends of the capacitor. Whether it is an electronic or pointer multimeter, the displayed value is instantly small, and then slowly increases. . The larger the capacitance, the slower the increase rate. If the resistance value of the capacitor is 0 or ∞ and there is no change, it can be judged that the capacitor is leaking or breaking down.

Observe whether the compressor moves (or abnormal noise) after turning it on, and feel whether the middle of the compressor is hot; check whether the compressor is "locked up". If necessary, use a rubber hammer or a small wooden stick to hit the middle of the compressor, and then turn it on again. Observe whether the compressor operates;

4. Fluorine leakage in the refrigeration system

a. Symptoms: The compressor and high-pressure pipe are hot, and the high and low pressures are often low. For example, serious fluorine leakage will cause a low-pressure alarm.

c. Treatment steps: Leaks must be checked and re-commissioning must be filled with fluorine.

(2) Air system failure

1. The air system has a pressure drop at the inlet and outlet of the equipment

Processing steps:

a. The inside of the evaporator is blocked by ice, and the evaporation pressure is low; adjust the evaporation pressure above 0.4MPa;

b. The filter element of the steam-water separator fails;

c. The compressed air pre-filter element fails;

d. The air pressure gauge is broken;

e. Serious air leakage in the drainage system

2. Poor water removal in the air system

Processing steps:

a. The compressed air inlet pressure is seriously low;

b. The drainage system does not drain, and the time setting of the electronic drain is short;

c. The float drainer is dirty and blocked, and the manual draining is not timely.

(3) Electrical system failure

1. High and low voltage switch circuit breaker

Processing steps: Manually reset and check the refrigeration system.

2. Thermal relay circuit breaker

Processing steps: Check the current direction of the thermal relay and check the actual current value.

3. The compressor protection module trips

Processing steps: Press the manual reset button to reset, wait for the boot time, and check the control circuit according to the electrical schematic diagram.

4. Turn on the air switch

Processing steps:

a. Check whether there is a short circuit or poor contact in the line causing phase loss;

b. Check the electromagnetic contactor;

c. Measure the actual operating current value;

d. Check the resistance value of the compressor motor to determine whether the compressor operates.

5. The control system fuse is blown

Processing steps:

a. Check the resistance value of the coil of the electronic drain;

b. Check the short circuit according to the schematic diagram of the control system.

6. The compressor does not run when connected to the power supply

Processing steps: Check the power phase sequence, and then check the schematic diagram.

(4) Failure of the drainage system

1. Ice blockage at the drain: adjust the evaporation pressure to the normal value.

2. Dirty blockage of the float drain: Clean the float drain.

3. The electronic drain does not drain: Check the coil of the electronic drain and the electrical schematic diagram.

※ The importance of the drainage system: When the condensed water is removed from the dryer, it cannot be drained in time. The flow rate of the air brings the condensed water out of the dryer to the user's gas point, bringing water in the air source. Therefore, the user should always use the manual drain button ESC to drain water, observe the drain time of the electronic drain, and reset the drain time.