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Common faults of refrigeration system of vacuum freeze dryer

July 15, 2022

The common faults of the refrigeration system of vacuum freeze dryer mainly include high pressure alarm, compressor motor overload, motor temperature too high, oil pressure difference alarm, water pressure alarm and the actual effect of expansion valve adjustment. Let’s talk about the causes and solutions of these common failures:


(1) High pressure alarm:


The amount of water in the water condenser is insufficient or the water temperature is too high; some scale is formed inside the water condenser, which reduces the heat conversion efficiency; the low-pressure pipe ruptures when the compressor is working, allowing air to enter the refrigeration pipe; refrigeration The valve of the pipeline is not fully opened, or the exhaust pipeline is blocked, causing the exhaust to be blocked; too much use of the refrigerator causes the exhaust pressure to be too large.


Solution: reduce the water temperature or increase the flow rate; clean the lower water condenser; make the refrigeration pipeline simple. If this operation cannot be carried out in the working state, you can open the stop valve above the water condenser first, and the water condenser Part of the air is released; that is, the valve on the compressor pipeline needs to be opened to the maximum; part of the refrigerator needs to be released.

 

 

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(2) The motor of the compressor is overloaded:


Reason: there are debris in the piston cylinder, which makes the piston not smooth, and the situation of holding the shaft and closing the cylinder occurs; the thermal load of the compressor is overloaded, which may be caused by steam sterilization and other operations; the thermal overload relay does not have timely reset.


Solution: Clean up the internal residue of the compressor in time; cool the compressor to the allowable temperature in time; reset the relay in time.


(3) Motor temperature is too high:


The reason is that the amount of air returned by the refrigerator is insufficient, resulting in insufficient cooling of the motor; the refrigerator is insufficient or lacking; the three-phase electric power supply of the compressor is unstable; the thermal protection module of the compressor has a problem; the pipeline for the liquid supply A blockage has occurred.


Solution: Restart the switch of the compressor; replenish the refrigerant in time; provide the power of the compressor as required; clear the blocked parts in time; replace the template if necessary.
(4) Alarm of oil pressure difference:


The reason may be that the relay of the oil pressure difference is not reset in time; if the refrigeration oil turns yellow or black, it may be that the refrigeration oil has deteriorated, causing the filter to be blocked; in addition, there is a problem with the oil return, which makes the compressor The amount of oil in the crankcase cannot be reached, and the oil pump cannot absorb oil.


Solution: perform manual reset; clean the filter and replace the refrigeration oil; hit the oil separator with a hard object, if it does not work, replace the separator.


(5) For the alarm of water pressure, the reason may be that the supply of cooling water is insufficient; or the relay of the water pressure is faulty.


Solution: In order to increase the external water supply pressure; check the pressure relay.


(6) For the failure of the expansion valve adjustment, the reason may be that the teeth of the internal adjustment gear are pulled sideways due to long-term force; the expansion valve is blocked, which makes the low pressure gauge of the compressor too low.


The solution is: knock the gear teeth until the gear teeth are parallel to the inner plane; disassemble the expansion hair and clean it up; check that the pipes and filters or valves are open.