The basic principle of freeze-drying machine
The working principle of a freeze dryer is mainly based on three steps: pre freezing, sublimation, and analysis.
Pre freezing: Quickly freeze the substance to be dried at low temperature to form solid ice crystals.
Sublimation: In a vacuum environment, ice crystals are directly sublimated into water vapor through appropriate heating, without passing through a liquid state.
Analysis: Further increase the temperature to remove a small amount of water bound to the surface of the substance.
Preparation work before operation
Equipment inspection: Ensure that all components of the freeze-drying machine are intact and undamaged, especially the vacuum pump and condenser.
Cleaning work: Clean the drying chamber and condenser to remove impurities that may affect the drying effect.
Sample preparation: Cut and package the substance to be dried according to the requirements, and ensure that it is suitable for freeze-drying.
Operation steps
Power on and pre cooling: Turn on the freeze-drying machine, set the pre cooling temperature, and wait for the cold trap temperature to reach the preset value.
Sample loading: Place the prepared samples into a drying chamber, ensuring sufficient spacing between the samples for gas flow during ice crystal sublimation.
Start the vacuum pump: Turn on the vacuum pump to reduce the air pressure in the drying chamber to the desired vacuum level.
Sublimation process: According to the properties and thickness of the sample, gradually increase the temperature of the heating plate to promote the sublimation of ice crystals.
Analysis process: After most of the ice crystals sublime, further increase the temperature of the heating plate to remove the remaining water.
End and shutdown: When the dryness of the sample reaches the required level, turn off the heating plate, stop the vacuum pump, and wait for the equipment to cool down before removing the sample.