Freeze-drying is a technique of drying by the principle […]
Freeze-drying is a technique of drying by the principle of sublimation. It freezes the material to be dried at a low temperature and then directly sublimes the frozen water molecules into a process of water vapor evolution under a suitable vacuum environment.
The material is always in a low temperature (freezing state) before drying, and the ice crystals are evenly distributed in the material. The sublimation process does not cause concentration due to dehydration, and avoids side effects such as foaming and oxidation caused by water vapor. The dry material is porous in the shape of a dry sponge, the volume is basically unchanged, and it is easily soluble in water and restored to its original state. Physical and biological denaturation of dry matter is prevented to the greatest extent. Operation Steps of Vacuum Freeze Dry Machine are as follows.
1.Turn on, main switch, and the refrigerator to cool down for 40~60 minutes;
2. Take out the pre-frozen material and put it on the drying rack;
3. Put the drying rack on the cold trap;
4.Check the plexiglass cover on the premise that the sealing ring is intact and free of debris;
5.Confirm that the drain/intake valve is closed;
6.Open the vacuum gauge and vacuum pump; the vacuum is reduced to less than 20Pal, and ensure that there is no abnormal noise during the operation of the vacuum pump.
7.After drying, open the “waterproof (intake) valve” and then close the “vacuum pump” (the valve outlet must be placed in a large enough container to collect the liquid discharged by the defrosting). Remove the plexiglass cover and collect the dried material.
Precautions of Vacuum Freeze Dryer during operation are as follow.
1.The refrigerator should not be closed during the whole drying process;
2.As physical differences, drying and pre-freezing time are different;
3.The material to be dried must not contain flammable, explosive and volatile organic matter. Do not contain high concentrations of strong acids and bases.
4.Check the oil level of the vacuum pump and compressor table. The vacuum pump oil needs to be kept clean.