During the use of a vacuum freeze dryer, it is usually necessary to release air before turning off the vacuum pump, in order to protect the vacuum pump and improve the drying effect.

Firstly, the purpose of venting is to eliminate gases and vapors that may be generated during the freeze-drying process. During the freeze-drying process, the moisture in the sample will transform into ice and directly into a gaseous state under vacuum conditions, which is called sublimation. Meanwhile, other gases, volatile substances, or solvents in the sample may also evaporate at low temperatures, forming gases. If these gases and vapors are not removed in a timely manner, they will affect the vacuum degree and even have a negative impact on the vacuum pump.

Secondly, releasing air before turning off the vacuum pump can protect its lifespan and performance. After long-term operation, vacuum pumps will generate certain wear and heat. If the vacuum pump is directly turned off without releasing air first, it will cause a sudden increase in internal pressure, which may have adverse effects on the sealing components and internal structure of the pump, and even cause malfunctions. By releasing air first and then turning off the vacuum pump, the pressure can gradually be restored to atmospheric pressure, reducing the impact on the vacuum pump and extending its service life.

In general, releasing air first and then turning off the vacuum pump is to protect the vacuum pump and improve the drying effect. This is a routine operation step in the vacuum freeze-drying process to ensure the stability, safety, and durability of the system. During the operation, please follow the instructions and operating standards of the equipment to ensure the effectiveness of the laboratory and the normal operation of the equipment.