Maintenance and care of freeze dryers

In addition to the quality of instrument products, effective maintenance can extend their service life. As a common refrigeration equipment in the laboratory, the utilization rate of freeze dryers is very high. In many important experiments, freeze dryers are the "great contributors" to pretreatment. The stability of its operation and service life depend to a large extent on whether the maintenance of the freeze dryer is correct and effective.

1. Maintenance and technology of refrigeration system
The main part of the refrigeration system is the maintenance of the refrigeration compressor. To ensure the normal operation of the compressor, the key is to make it operate under normal operating conditions, such as high pressure, high pressure exhaust temperature, oil pressure, compressor frost degree, whether the current of the running motor exceeds the standard, etc. When some of these parameters exceed the operating parameter indicators of the compressor, it means that there are certain problems with the compressor and necessary maintenance is required.

The maintenance of the compressor mainly includes:
1. Replace the refrigeration compressor oil and filter. To determine whether the compressor oil needs to be replaced, you can release a certain amount of oil for oil quality analysis and oil acidity measurement and inspection, or use regular replacement. When changing the oil, it should be noted that the brand of the oil should be consistent with the oil being replaced. Otherwise, it is difficult to guarantee whether the oil of different brands will have other physical and chemical reactions with the original compressor oil, which may affect the operation of the system and the compressor.

2. When the refrigeration compressor has poor refrigeration effect, such as the exhaust temperature of the compressor is too high and the refrigerant is too little, at this time, it is necessary to first consider whether the refrigeration system has refrigerant leakage and whether air is mixed in the system. At this time, the machine maintenance should mainly consider eliminating the leakage point of the system, then remove the water mixed in the system, and replace the acid-removing drying filter of the system pipeline.

2. Maintenance of the vacuum system
The vacuum system is the quality guarantee of the sterility of the freeze-dried sample of the freeze dryer. The maintenance of the vacuum system should mainly focus on the operating parameters such as the vacuum system's vacuum pumping rate, the ultimate vacuum degree, and the vacuum leakage rate of the freeze-drying system. Pay attention to the changes in the vacuum degree during the use process. The maintenance work mainly includes regular replacement of vacuum pump oil, regular testing of the ultimate vacuum value and the leakage rate parameters of the vacuum system, regular inspection of the reliability of the valve seals of each pipeline connected to the vacuum system, and replacement of the seals when necessary. If there is an abnormal vacuum change in the vacuum system, it is necessary to check the freeze dryer vacuum system in sections and use the elimination method to check the vacuum leaks in the system.

3. Maintenance of the automatic control system
The automatic control system of the freeze dryer is the key to ensure the smooth progress of freeze-dried products and ensure product quality. At present, some freeze dryer products are equipped with remote online diagnosis and automatic repair freeze dryer control programs, which can realize remote monitoring and diagnosis of the operation of the freeze dryer through network links, and can more effectively solve the problems of the automatic system.

In daily production, operators should also pay attention to the main process parameters such as the inlet and outlet temperature and vacuum degree of the freeze drying chamber, the temperature and vacuum degree of the cold trap, and the main operating parameters of the compressor and other systems (such as the suction and exhaust pressure, temperature, oil pressure difference of the compressor, refrigerant liquid temperature, cooling water inlet and outlet temperature, solution pump inlet and outlet pressure, etc.) Whether it is normal, and keep the equipment in a clean state, especially the cleanliness of the control room, and keep its appropriate temperature and relative humidity to ensure the normal operation of computer and other control equipment.