Freeze-dryer Epsilon 1-4 LSCplus
Freeze-dryer Epsilon 2-4 LSCplus
12 Glossary
Version 07/2022, Rev. 3.0 of 20/07/2022
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Translation of the original operating manual
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12 Glossary
Aeration, stoppering, storage
"Aeration, stopperting, storage" means automated sealing of the product
vials with previously inserted rubber stoppers under partial vacuum and
subsequent storage on the shelves at defined conditions as an integral part
of a freeze-drying program. This is why this option can only be used in
combination with a programmer module and if the freeze-dryer is equipped
with an automatic aeration valve and a hydraulic shelf movement system.
Comparative pressure measurement
During the
→
sublimation
, i.e. when the concentration of water vapour
molecules is rather high in the atmosphere, the value that is provided by
the gas-type dependent vacuum sensor of the "Pirani" type (e.g. Thyracont
VCP 63) deviates from the value that is provided by a capacitive vacuum
sensor (e.g. Pfeiffer CMR363). When the proportion of water vapour
molecules decreases towards the end of the main drying phase, the two
sensors fall increasingly in line with one another.
The comparative pressure measurement is often used as a criterion for the
automatic switching from the main drying phase to the final drying phase as
well as for identifying the end of the process.
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
Freezing and drying of the product on several temperature controlled
shelves inside a separated drying 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 so-called
→
pressure increase test
for determining the end of the drying process.
Eutectic point
The eutectic point is the point at which a homogenous mixture (e.g. an
eutectic alloy) passes directly from the liquid to the solid phase without the
formation of a crystal mixture that consists of different phases.
Leakage test
The leakage test enables the chamber of the freeze-dryer to be tested for
tightness in view of any gaseous or liquid media. Since absolutely tight
components simply do not exist, a leak rate is determined. The parameters
for the leakage test have been developed by Martin Christ Gefrier-
trocknungsanlagen GmbH specifically for freeze-dryers. In a first step,
these parameters (vacuum, ice condenser temperature) must be reached.
It is not until the conditions are fulfilled that the pressure control valve
closes. Then, the actual leakage test is performed in a second step. The
leak rate that is calculated after the end of the test provides information
concerning the tightness of the system.
