Patent ID: 9459044
Filing Date: 2016-10-04
CPC Classification: F26B

Claim Text:
1. A freeze drying method comprising: decreasing pressure in a chamber to a first vacuum pressure, the chamber containing a material containing solid water; as a result of reaching the first vacuum pressure, a control system automatically activating a heater and heating the material without melting the solid water; sublimating the solid water to gaseous water and increasing pressure to a second vacuum pressure greater than the first vacuum pressure; cooling an interior surface of the chamber to below the material temperature; condensing and freezing at least a portion of the gaseous water on the interior surface of the chamber; and as a result of reaching the second vacuum pressure, the control system automatically deactivating the heater and, as a result, repeating a decrease in pressure to the first vacuum pressure, pressure-activated heater activation as a result of reaching the first vacuum pressure, material heating, water sublimation, and increase in pressure to the second vacuum pressure and accomplishing pressure-activated heater cycling.