คู่มือแก้ไขปัญหาเครื่องทำแห้งเยือกแข็งสุญญากาศ: 20 ข้อบกพร่องทั่วไป

Freeze dryers are used broadly in fruit, meat, pet food and herb processing. Systematic fault diagnosis requires understanding of 7 subsystems.

1. ระบบทำความเย็น

Fault 1: Cold Trap Below -35°C

Cause	Solution
Refrigeration unit failure	Check compressor operation
Low refrigerant	Leak test, recharge to spec
Expansion valve fault	Clean or replace, adjust superheat
Ice build-up	Run defrost cycle

Fault 2: Insufficient Compressor Capacity

Overhaul or replace compressor; section-by-section leak test.

Fault 3: High-Pressure Alarm (Cascade)

Clean condenser fins and fan; check cooling tower, increase water flow.

2. ระบบสุญญากาศ

Fault 4: Chamber Vacuum > 26Pa

Check pump oil/blades; helium leak detection for seal leaks.

Fault 5: Roots Pump Overload/Noise

Pre-pump must reach <2000Pa before roots pump starts.

Fault 6: Vacuum Fluctuation

Check pump oil circuit; helium leak test; stabilize cold trap temperature.

3. ระบบทำความร้อน

Fault 7: Uneven Shelf Temperature (>±2°C)

Check thermal oil circulation pump; clean shelf channels; calibrate sensors.

Fault 8: Slow Shelf Heating

Check heater power; purge trapped air from oil line.

Fault 9: Overshoot Temperature

Reset PID parameters; replace SSR/contactor if stuck.

4. คุณภาพกระบวนการ

Fault 10: Product Collapse/Melt

Reduce heating rate — keep 5~10°C below eutectic point.

Fault 11: Long Cycle

Optimize pre-freeze curve; reduce fill depth (≤15mm).

Fault 12: High Residual Moisture

Extend desorption time; improve vacuum level.

Fault 13: Severe Shrinkage

Increase freezing rate; re-measure eutectic point.

5. ระบบละลายน้ำแข็ง

Fault 14: Incomplete Defrost

Replace heater; clean spray nozzles; insulate drain line.

Fault 15: Poor Drainage

Clear drain pipe; ensure slope ≥3%; increase pipe diameter.

6. ระบบไฟฟ้า/ควบคุม

Fault 16: Process Curve Anomaly

Restart PLC; check touchscreen communication; ground shielding.

Fault 17: Temperature Sensor Drift

Calibrate or replace; correct compensation parameters.

Fault 18: Vacuum Gauge Contamination

Clean and dry gauge; replace filter element.

7. ระบบกลไก

Fault 19: Butterfly Valve Seal Failure

Replace seal ring; repair pneumatic actuator.

Fault 20: Door Seal Leak

Check hydraulic system; replace seal ring; realign door.

Summary

System	Faults	Key Indicator
Refrigeration	3	Cold trap -35°C
Vacuum	3	Chamber ≤26Pa
Heating	3	Shelf Δ±2°C
Process	4	Eutectic point
Defrost	2	Defrost effectiveness
Electrical	3	Process curve
Mechanical	2	Seal integrity

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Compiled by บริษัท Yuanxian Machinery technical team. Refrigerant handling and electrical repairs require certified personnel.