1. The high pressure of the freeze dryer is too high, and the high pressure alarm
Reason and solution:
a. There is too much refrigerant and the exhaust pressure is high, and part of the refrigerant should be released.
b. The cooling water temperature is high, the flow is insufficient or the water condenser is scaled.
c. There is leakage in the low-pressure section of the refrigeration pipeline, and air is sucked in; the high-pressure exhaust valve is not fully opened or damaged, resulting in poor exhaust.
It can be reset through the alarm reset button, and the button switch is on the high pressure pressure relay.
2. Oil pressure difference alarm
Reason and solution:
a. The oil return is not smooth, resulting in insufficient oil level in the crankcase of the compressor, and the oil pump cannot absorb oil. Generally, a new oil separator is required.
b. The oil is dirty, causing the oil pump filter to be blocked. The oil needs to be changed and the oil filter cleaned.
c. The oil pressure difference relay fails. Replace the oil differential pressure relay with a new one.
d. The oil pump fails. Replace the oil pump with a new one.
e. The evaporation of the refrigeration system is not good, and the refrigerant enters the crankcase. Bringing refrigerated oil into the system, causing the oil pressure to be too low. Close the liquid supply valve at the outlet of the condenser or adjust the thermal expansion valve (increase the superheat of the system).
After the compressor starts 90s, the oil pressure difference relay will work. If there is no oil pressure difference, it will alarm. After the alarm, the reset button on the oil pressure difference relay can be reset to eliminate the alarm.
3. Thermal protection of compressor (motor temperature exceeds 85℃)
Reason and solution:
There is insufficient air return to the system and the motor is not being adequately cooled.
a. Adjust the intercooling expansion valve, increase the circulation volume of the system, and make the motor fully cool.
b. Check whether the liquid supply pipeline is blocked (liquid supply cut-off valve, dry filter, solenoid valve, filter screen before expansion valve, etc.) If there is blockage, it should be solved.
c. Check whether the return air pipeline and the suction filter of the compressor are blocked, and repair if there is any blockage.
d. Check whether there is a lack of refrigerant, if there is a lack of refrigerant, it needs to be supplemented.
After the electronic thermal protection alarm, the 220V control power supply of thermal protection must be turned off and restarted to eliminate the alarm.
4. Water pressure alarm
Reason and solution:
a. The cooling water pressure is lower than the pressure set by the water pressure relay. Make sure the cooling water pressure is higher than the pressure set by the water pressure relay. The set pressure of the water pressure relay can be appropriately adjusted under the condition that the high pressure of the compressor does not alarm with the cooling effect.
b. The water pressure relay fails. Replace the water pressure relay. As long as the water pressure is higher than the pressure set by the water pressure relay, the alarm is cleared.
5. The compressor of the freeze dryer cannot be started
Reason and solution:
a. There is an alarm among high pressure alarm, oil pressure difference alarm, electronic thermal protection and water pressure alarm. Find the cause of the alarm and eliminate the alarm.
b. The instantaneous starting current is too large, resulting in thermal overload protection or air switch protection. Find out the cause of the large current, and reset the thermal overload to start.
c. The compressor crankshaft is bitten to death, and the piston cylinder is bitten to death. Repair the compressor.
d. The control system is faulty, and there is no output control for the compressor. Control system failure should be solved by our company's software personnel.
e. Electrical system faults such as PLC faults, AC contactor faults, etc. After confirming that the electrical components are faulty, they are generally replaced to solve the problem.
6. The compressor suddenly stops automatically when it is running
Reason and solution:
a. There is at least one alarm for high pressure alarm, oil pressure difference alarm, electronic thermal protection and water pressure alarm during operation.
b. AC contactor failure, overload protection, and compressor motor burn out suddenly during operation.
c. Liquid shock or oil shock occurs during operation, and the piston or crankshaft is seized.
d. The control program is unstable instantaneously during operation, and there is no output suddenly.
7. The refrigeration effect of the freeze dryer refrigeration system is not good
Reason and solution:
a. The expansion valve is opened too large or too small. If the expansion valve is opened too large, the compressor itself has serious frost accumulation, and the liquid flow is too large. If the expansion valve is opened too small, the liquid flow is insufficient. Adjust the expansion valve to make the compressor reach the best working condition.
b. The refrigeration system is blocked, such as filter blockage, expansion valve blockage, related valves not opened or not fully opened, solenoid valve failure, etc. Find the location and cause of the blockage and clean it in time.
c. The refrigerant is not enough. Add the right amount of refrigerant.
d. The paper pad on the upper part of the compressor valve plate or the lower part of the cylinder is broken down or broken or the compressor suction and exhaust valve plates are broken. Replace with new paper pad or exhaust valve plate.
Application of freeze dryer machine
