Single-chamber methodAt the single-

Single-chamber method
At the single-chamber method, the freezing as well as the subsequent
drying of the product are both performed in the ice condenser chamber.
The sample is frozen as a result of the low temperature of the ice
condenser
(–55°C in the case of one-stage systems or –85°C in the case of two-stage
systems). The inside of the chamber can be cooled to approximately –20°C
or –40°C. The moderate supply of the frozen sample with energy, which is
necessary during the main drying phase, is ensured by heatable shelves on
which the product is placed.
Double-chamber method
Drying on shelves outside the ice condenser chamber is referred to as a
double-chamber system. The advantage compared to the o singlechamber
method is the considerably higher product capacity. In addition,
the product chamber can be isolated from the ice condenser chamber by
an intermediate valve in order to perform a so-called o pressure increase
test for determining the end of the drying process. In freeze-dryers without
an active shelf cooling, the samples need to be pre-frozen externally, e.g. in
a deep-freeze or freezer cabinet. After the transfer of the product into the
freeze-dryer, the actual o sublimation is started.