Process and device for determining the end of a primary stage of freeze drying

摘要

A tray-type freeze drying device determines the end of a first stage of a freeze drying process by regularly and drastically reducing the pressure surrounding the product being freeze dried. No decrease in product temperature during the reduction in pressure indicates the completion of the sublimation of water from the product and the end of the first stage of drying. A decrease in product temperature during the drastic reduction in pressure indicates the need to continue the sublimation procedure and the first stage of drying.