Why can't the compressor stop when using the vacuum freeze dryer?

Vacuum freeze dryer is a dryer with refrigeration function. In the pharmaceutical industry, dryers play an important role in reducing the possibility of material oxidation and deterioration, eliminating bacteria in materials, ensuring good preservation of the original shape of materials, and further reducing pollution risks. At present, it is applicable to the drying of raw materials, Chinese herbal pieces, biological, pharmaceutical intermediates and other materials. Of course, food can also be used as freeze-dried products, but food grade models should be used.

When the vacuum freeze dryer is working, it is necessary to freeze the materials containing water in advance to reduce the temperature and freeze them into solid state, and then sublimate the water vapor under the action of the vacuum pump. During the freezing and cleaning process, the water vapor will frost, and defrost can be carried out after the work is completed.

Therefore, its volume will not change after drying, and its weight will certainly be reduced, because the water has been sublimated, and the porous structure inside the material needs to digest and absorb heat during sublimation. The temperature of the product itself will be reduced, and the sublimation rate will be reduced, thus increasing the sublimation rate and reducing the drying time. All drying will be carried out at a lower temperature.

Compared with the products before drying, the properties of the dried products are very different. The freeze-drying principle is basically carried out below 0 ℃, that is, in the frozen state of the product. The analytical drying is generally not more than 60 ℃. Under vacuum conditions, when the water vapor is sublimated directly, the drug remains in the frozen ice shelf, forming a spongy porous structure, so its volume is almost unchanged after drying. Before reuse, as long as water is added, it will return to the state before freeze-drying.

Why is the compressor always on during vacuum pumping? This is because keeping the low temperature state is conducive to the water vapor generated during the continuous sublimation process after the water in the sample freezes and then freezes again in the cold trap, and defrosts after the freeze-drying is completed. Just to keep the temperature low.