This article will provide an in-depth analysis of common malfunctions in freeze dryers and propose effective solutions, while also discussing key points for equipment maintenance, offering valuable insights for businesses.
I. Analysis of Common Malfunctions
(1) Refrigeration System Malfunctions
Malfunction symptoms: The freeze dryer's refrigeration effect is poor, the pre-freezing temperature cannot reach the set value, or the condenser temperature is too high during the sublimation drying stage, preventing effective water vapor collection.
Cause analysis: Refrigeration system malfunctions are usually caused by refrigerant leakage, compressor failure, poor condenser heat dissipation, etc. First, check the refrigerant lines for leaks. This can be done through pressure testing and applying soapy water. If a leak is found, repair it promptly and replenish the refrigerant. Second, check the operating status of the compressor, checking if the current and voltage are normal, and if the suction and discharge pressures meet the specified values. If there are any abnormalities, it may be due to damage to internal compressor parts, requiring timely repair or replacement. In addition, excessive dust on the condenser surface or poor ventilation can lead to poor heat dissipation, affecting the refrigeration effect. The condenser surface should be cleaned regularly to ensure good ventilation.
(2) Vacuum System Malfunctions
Malfunction symptoms: The freeze dryer's vacuum pumping speed is slow, unable to reach the set vacuum level, or the vacuum level fluctuates significantly during the freeze-drying process.
Cause analysis: Vacuum system malfunctions are mainly related to vacuum pump failure, vacuum line leaks, and poor sealing of vacuum valves. First, check the working status of the vacuum pump, checking if the oil level is normal and if the vacuum pump oil has deteriorated. If the oil level is too low or the oil quality is poor, replenish or replace the vacuum pump oil promptly. Also, check for abnormal noise or vibration at the vacuum pump's exhaust port. If present, it may indicate wear of internal vacuum pump parts, requiring repair or replacement. For the vacuum lines, carefully check all connection points for leaks. A helium mass spectrometer leak detector can be used for accurate detection. After finding the leak, seal it promptly. In addition, the sealing performance of the vacuum valves also affects the vacuum level. Regularly check if the valve's sealing rings are aging or damaged, and replace them if necessary.
(3) Heating System Malfunctions
Malfunction symptoms: The freeze dryer's temperature cannot rise to the set value during the analytical drying stage, or the temperature control is unstable, resulting in excessively high or low temperatures. Cause Analysis: Common causes of heating system failures include damaged heating elements, faulty temperature sensors, and malfunctioning thermostats. Check the heating elements (such as heating wires, heating plates, etc.) for open or short circuits using a multimeter. If the heating element is damaged, replace it promptly. The temperature sensor is a critical component for monitoring temperature; a faulty sensor will lead to inaccurate temperature control. Check if the sensor's wiring is loose and if the sensor is functioning correctly; replace the temperature sensor if necessary. The thermostat controls the operation of the heating system; a malfunctioning thermostat will prevent the temperature from being adjusted according to the set program. The thermostat needs to be calibrated or replaced.
(4) Control System Failure
Fault Symptoms: The freeze dryer's control system exhibits problems such as no display on the operation interface, program execution errors, inability to set parameters, or inaccurate parameter display.
Cause Analysis: Control system failures may involve both hardware and software issues. For hardware, check if the control circuit board, display screen, buttons, and other components are damaged. If damaged, replace the corresponding hardware promptly. For software, check if the control program has errors or is missing. Try restarting the control system or reinstalling the control program. Also, ensure that the communication between the control system and other equipment (such as the refrigeration system, heating system, vacuum system, etc.) is normal. Check if the communication lines are properly connected and if the communication protocols match. If there are problems, repair the communication fault promptly.
II. Maintenance and Upkeep of the Freeze Dryer
(1) Regular Equipment Cleaning
Regularly clean the inside of the freeze dryer's chamber, the water trap, condenser, and other components to remove dust, dirt, and residual drug impurities. Use specialized cleaning agents and tools during cleaning, avoiding corrosive cleaning agents that could damage the equipment surface. For the inside of the chamber, wipe with a damp cloth; for stubborn stains, use a neutral detergent. After defrosting, the water trap should be cleaned promptly to remove ice and accumulated water, keeping the inside clean and tidy. Dust on the condenser surface can be blown away with compressed air or cleaned with a soft brush.
(2) Inspection and Replacement of Consumable Parts
Regularly check the condition of consumable parts of the freeze dryer, such as sealing rings, vacuum pump oil, heating elements, and temperature sensors. The sealing rings will age and deform after prolonged use, leading to a decrease in sealing performance. They should be inspected regularly and replaced promptly. Vacuum pump oil will gradually deteriorate during use, affecting the performance of the vacuum pump. The vacuum pump oil should be replaced promptly according to the specified time and oil quality. Heating elements and temperature sensors also have a limited lifespan. When their performance deteriorates or they are damaged, they should be replaced promptly to ensure the normal operation of the equipment.
(3) Calibrating Equipment Parameters
Regularly calibrate key parameters of the freeze dryer, such as temperature, pressure, and vacuum level, to ensure the accuracy and reliability of the parameters. High-precision calibration instruments can be used to calibrate the equipment. The calibration process should strictly follow the operating procedures, and the calibration results should be recorded and analyzed. If significant parameter deviations are found, adjust the relevant settings of the equipment or replace the faulty components to restore the equipment parameters to the normal range.
(4) Maintaining the Electrical System
Regularly check whether the electrical wiring of the freeze dryer is securely connected and free from aging or damage; check whether the working status of electrical components (such as relays, contactors, fuses, etc.) is normal, and whether there are any abnormal conditions such as overheating or unusual noises. Replace aging or damaged electrical wiring and components promptly; clean the inside of the electrical control cabinet to prevent dust accumulation from affecting the normal operation of electrical components.
(5) Maintaining Operating Records
Establish a detailed operating record archive for the freeze dryer, recording information such as the equipment's start time, stop time, various parameters during operation, fault occurrences, and corrective actions. By analyzing the operating records, potential problems in the equipment's operation can be identified in a timely manner, and the operating patterns of the equipment can be summarized, providing a basis for equipment maintenance, repair, and fault diagnosis.