Condensers water vapor completely frozen

The flow of water vapor should deviate as little as possible before the first condenser surface. The condenser design has to ensure that the water vapor is completely frozen and the remaining water vapor pressure is practically equal to the vapor pressure at the ice surface. This can only be achieved if the vapor passes over several condenser surfaces in series. 

The condenser temperature (T o) and its related vapor pressure (e.g., —50°C at 0.04mbar, -60°C at 0.01mbar) will normally define the lowest pressure to be reached in, for example, 20 min. A prolonged evacuation time can be related to water from sterilization or from condenser defrosting which was not completely drained, was frozen during evacuation below 6mbar, and hides in an area with limited heat input. The lowest pressure to be reached will depend on the ice temperature at an equilibrium between heat input into and possible amount of sublimation from the hide-out. Very often this pressure will be between 1 and O.lmbar. 

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