The refrigeration system of Lyophilization Equipment co […]
The refrigeration system of Lyophilization Equipment cools the (ice) condenser located inside the Lyophilization Equipment. The refrigeration system can also be employed to cool shelves in the product chamber for the freezing of the product.
The vacuum system of Lyophilization Equipment consists of a separate vacuum pump connected to an airtight condenser and attached product chamber.
Control systems vary in complexity and usually include temperature and pressure sensing ability. Advanced controllers will allow the programming of a complete “recipe” for freeze drying and will include options to monitor how the freeze drying process is progressing. Choosing a control system for the freeze dryer depends on the application and use (i.e. lab vs. production).
Product chambers are typically either a manifold with attached flasks, or, a larger chamber with a system of shelves on which to place the product.
The purpose of the condenser is to attract the vapors being sublimed off of the product. Because the condenser is maintained at a lower energy level relative to the product ice, the vapors condense and turn back into solid form (ice) in the condenser. The sublimated ice accumulates in the condenser and is manually removed at the end of the freeze drying cycle (defrost step). The condenser temperature required is dictated by the freezing point and collapse temperature of the product. The refrigeration system must be able to maintain the temperature of the condenser substantially below the temperature of the product.
In the Lyophilization Equipment, the condenser can be located inside the product chamber (internal condenser) or in a separate chamber (external condenser) connected to the product chamber by a vapor port.
Manifold Lyophilization Equipment rely on ambient conditions to provide the heat of sublimation to the product. This heat input does not melt the product because an equivalent amount of heat is removed by vaporization of the solvent. Advanced Lyophilization Equipment can provide a heat source to control/expedite the drying process and they can also employ the refrigeration system to allow freezing of product inside the unit.