Freeze drying method

摘要

A method of controlling the primary drying stage in a freeze drying apparatus having a shelf and bulk product or a number of vials in different areas on the shelf which contain product to be freeze dried. Temperature sensors are positioned in selected locations or vials which are representative of the different bulk product areas or the positions of all of the vials in different areas of the shelf. The temperature sensors are monitored and compared to determine the selected location or vial having the highest temperature while the temperature sensor therein is still in ice. The shelf temperature is controlled based on the selected location or vial with the highest temperature so long as the temperature sensor therein is still in ice. When the temperature sensor in the highest temperature selected location or vial is no longer in ice, another selected location or vial with the highest temperature and a temperature sensor therein that is still in ice is then used to control the shelf temperature.