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The principle of the four-ring freeze-drying experimental freeze-drying machine is: freeze-drying is a technology that uses the principle of sublimation for drying.
Direct sublimation becomes the process of water vapor escaping
.
The product obtained by freeze-drying is called lyophilisate and the process is called freeze-drying
.
The substance is always at a low temperature (frozen state) before drying, and the ice crystals are evenly distributed in the substance.
The sublimation process will not cause condensation due to dehydration, and avoid side effects such as foaming and oxidation caused by water vapor
.
The dry substance is in the form of a dry sponge, the volume is basically unchanged, and it is easily soluble in water and returns to its original state
.
Physicochemical and biological denaturation of dry substances is largely prevented
.
Precautions for the four-ring freeze-drying experimental freeze-drying machine 1.
The surface area of the sample should be expanded as much as possible, and it should not contain acid and alkali substances and volatile organic solvents; 2.
The sample must be completely frozen into ice, if there is residual liquid, it will cause vaporization and spray ; 3 Note that the cold trap is about minus 65 degrees, it can be used as a low temperature refrigerator, but you must wear thermal gloves to prevent frostbite; 4 Before starting the vacuum pump, check whether the water outlet valve is tightened, the inflation valve is closed, and the contact between the plexiglass cover and the rubber ring Whether the surface is clean and free of dirt and well sealed; 5 In general, the machine should not be used continuously for more than 48 hours; 6 During the freezing process, the temperature of the sample gradually decreases.
Continue drying to shorten drying time
.
Precautions: Do not switch on and off frequently during operation.
If the refrigerator stops running due to misoperation, it cannot be started immediately.
Wait at least 20 minutes before starting again, so as not to damage the refrigerator
.
After each freeze-drying, after the ice on the cold trap coil turns into water, clean it with a towel.
After freeze-drying, unscrew the "inflating valve" to inflate the cold trap slowly, so as not to damage the vacuum gauge
.
