Freeze dryers may encounter various malfunctions during use. The following is a detailed description of common malfunctions and their solutions:

1、 Vacuum system malfunction

1. Insufficient vacuum degree

-Reason: Vacuum pump oil contamination or low oil level; The aging of the sealing ring leads to air leakage; The high temperature of the cold trap affects the condensation efficiency of water vapor.

-Solution: Replace or replenish the vacuum pump oil, check the oil level window; Replace the fluororubber sealing ring; Reduce the temperature of the cold trap to below -50 ℃ and check the refrigeration system.

2. Abnormal noise or jamming of vacuum pump

-Reason: Water or impurities entering the pump chamber; Rotor wear or spring fracture; Motor overload.

-Solution: Drain the water from the pump and replace the lubricating oil; Disassemble and inspect the rotor clearance, replace damaged components; Check the current and repair the bearings or pump head.

2、 Refrigeration system malfunction

1. Insufficient cooling capacity

-Reason: refrigerant leakage or insufficient; The displacement of the compressor decreases; The scaling of the condenser leads to poor heat dissipation.

-Solution: Supplement refrigerant and perform leak detection and repair of pipelines; Replace worn suction valve plates or piston rings; Clean the condenser dirt to improve heat exchange efficiency.

2. Compressor abnormal noise or vibration

-Reason: Bearing damage; Coupling alignment deviation; Lubricating oil contamination.

-Solution: Replace the bearing; Adjust the coaxiality of the coupling; Replace the clean lubricating oil.

3、 Heating system malfunction

1. Uneven or unable to raise the temperature of the partition

-Reason: Heating tube open circuit; Temperature sensor offset; The solid-state relay is damaged.

-Solution: Use a multimeter to check the resistance of the heating tube; Calibrate or replace the temperature sensor; Replace the relay and check the control board signal.

2. Slow heating rate

-Reason: Damaged insulation layer; Heating power attenuation.

-Solution: Repair the insulation layer or install insulation cotton; Raise the voltage to within 10% of the rated value and replace the heating plate if necessary.

4、 Control system malfunction

1. Program running abnormally

-Reason: PLC program error or battery low; Touch screen communication interruption; The sensor signal is interfered with.

-Solution: Reset PLC program and replace battery; Check the RS485 communication cable connection; Keep the signal lines of the shielding control cabinet away from the interference source.

2. Abnormal parameter display

-Reason: The vacuum gauge is damp or the probe is contaminated; Loose wiring leads to signal drift.

-Solution: Dry the vacuum gauge and calibrate the zero point; Tighten the aviation plug and check the grounding of the shielding layer.

5、 Operational related issues

1. Poor freeze-drying effect of samples

-Reason: Insufficient pre freezing; The sublimation rate is too fast; The loading is too thick.

-Solution: Extend the pre freezing time; Control the heating rate in stages; Reduce the thickness of the material and increase stirring.

2. Severe frost return after shutdown

-Reason: Failure to execute defrosting procedure; The pneumatic valve is not tightly closed.

-Solution: Start up and execute high-temperature defrosting; Check the sealing of the solenoid valve and clean the ice residue.

Through the above systematic fault analysis and solutions, the operational stability of the freeze dryer can be effectively improved, ensuring production efficiency and product quality.