Industrial-scale freeze drying requires robust processes that are initially developed on pilot systems and then scaled up. The objective is to develop drying recipes (profiles of vacuum and shelf temperature versus time) that allow the best possible quality to be achieved in the shortest possible time.
Pilot systems must therefore have the same technology and geometry as the subsequent production freeze dryer, such as rectangular product chambers and shelves chilled or heated by liquid media.
Development tools for time-saving optimisation include:
- Temperature sensors, in particular wireless product temperature measurement (WTMplus 2.0) devices, which avoid distortion of the readings due to sensor cables
- LyoControl for determination of the solidification point (with crystalline or amorphous substances), which is a key input quantity for the drying recipe
- Vapour measurement in the gas chamber (e.g. using a mass spectrometer) for determination of the drying endpoint
- Pressure rise test in the partitioned-off product chamber
- Comparative pressure measurement with different types of vapour-sensitive gauges (Pirani and capacitive)
- Individually stopperable shelves for obtaining statistical data over a large number of specimens. All vials on a shelf are stoppered to terminate the process for that set. The remainder continue drying.
- Sample extraction device (lock) to enable ongoing quasi-online product quality control without disturbing the other vials