The control system of a freeze drying system takes on many different forms. Controls may be completely manual, semi automatic, and completely automatic,

Manual controls usually consist of switches for major functions like freezing, condenser, vacuum, negative shelf control, vacuum pump, stoppering, or may be combined in functionality and be labeled Freeze, Evacuate, heat up, or some other combination, to allow one to switch on each function, to accomplish freeze drying manually. Normally there are shelf temperature controllers which are either single point or microprocessor controlled generating ramps and steps for shelf temperature excursions. Sometimes these are connected to a series of switches, or discrete outputs that allow sequencing nearly becoming automatic, or semi automatic in functionality. If the switching mechanism is a PLC then normally the dryer is completely automatic, and the “switches” may operate by mouse click. The system may be recipe driven with many different levels of complexity, with or without failsafe mechanisms built in to provide safety, with analog inputs and outputs, and perhaps even cascade type control systems, where one variable depends upon one or more process parameters.

Applewood Scientific have resources to train operators, write protocols, diagnose and troubleshoot control systems and to be your resource. We are also able to help you validate your control system by performing the control system qualification protocol [That you purchased from the vendor or have written] that ensures that the matrix of operation, data acquisition system, screens, all correspond to the intended device, sequence, function, inputs and outputs thereby reducing risk and improving product quality.   Question: Do you really know what that red emergency stop switch does in all of the operational modes such as during freezing, sterilzation with steam, while cleaning in place, during a vacuum leak rate test or filter sterilzation sequence?  Question:  Do you really know if the door closing safety switches are all functioning as required?

Please contact Applewood Scientific for any issues dealing with your freeze drying controls.