Freeze-drying, or lyophilization, is the process of freezing a material then sublimating any frozen liquid directly from solid to gas. The method is often used to preserve food and pharmaceuticals, as it allows products to be easily stored and transported without requiring constant refrigeration.
Vacuum pumps are required for this process, and should be sized according to the freeze-dryer. If the pump’s flow rate is too high, then vapor will be pulled through the freeze-dryer’s condenser too quickly, reducing its efficiency. It is also important to clean the condenser after each run to prevent sublimation of frozen chemicals into the vacuum pump. Freeze-dryer applications require an ultimate vacuum of 10-1 to 10-3 mbar, which can be achieved with single- and two-stage rotary vane pumps or ChemStar Dry.