Freeze Dryer, also known as Lyophilizer, is widely used for pharmaceutical and biological industries. Freeze drying technology, also known as lyophilisation or cryodesiccation, is a low temperature dehydration process that involves freezing the product, lowering pressure, then removing the ice by sublimation. This is in contrast to dehydration by most conventional methods that evaporate water using heat. A freeze-dryer consists of  a vacuum chamber, shelves, process condenser, shelf-fluid system, refrigeration system, vacuum system, and control system. There are four stages in the complete freeze drying process: pretreatment, freezing, primary drying, and secondary drying. Usually, the freezing temperatures are between −50 °C (−58 °F) and −80 °C (−112 °F).