Freeze-dryer Alpha 3-4 LSCbasic
12 Glossary
Version 11/2018, Rev. 1.2 of 05/03/2019
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Translation of the original operating manuel
12 Glossary
Cold trap operation
Cold traps
are used for the condensation of moisture or solvents in
combination with vacuum pumps. CHRIST freeze-dryers can be used as
cold traps.
Desorption
Desorption (from Latin de-sorbere, sorbere = sup up, suck in) describes a
phenomenon whereby molecules are released from the surface of a solid.
In order to be able to desorb, the particle must have, or be provided with, a
sufficient amount of energy in order to overcome the binding energy.
Double-chamber method
Drying on shelves outside the ice condenser chamber is referred to as a
double-chamber system. The advantage compared to the
single-
chamber 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
pressure increase test
for
determining the end of the drying process. In freeze-dryers without active
shelf cooling, the samples need to be prefrozen externally, e.g. in a deep-
freeze or freezer cabinet. After the transfer of the product into the freeze-
dryer, the actual
sublimation
is started.
Eutectic point
The eutectic point is the point at which a homogeneous mixture (e.g. a
eutectic alloy) passes directly from the liquid to the solid phase without the
formation of a crystal mixture that consists of different phases.
Reference designation
Within the life cycle of industrial systems, a uniform equipment identification
system is required for planning, design, implementation, operation,
maintenance and dismantling so that all of the objects within the system
can be clearly identified at any time. The reference designations (also
known as device tags) are affixed to the equipment or components and
entered into the technical documents (e.g. circuit diagram).
Safety pressure
Since the vacuum has a dominating influence on the product temperature,
Martin Christ Gefriertrocknungsanlagen GmbH has integrated a safety
pressure feature into the freeze-dryers in order to ensure the protection of
the product. If the pressure inside the drying chamber increases too
strongly so that it exceeds the safety limit, the energy supply of the shelves
will be interrupted and the sublimation process slows down. This prevents
the product from melting.
The safety pressure value that is entered should correspond to a
temperature value that is 5°C below the melting point of the product on the
vapour pressure curve for ice and water.
