TANNER Scientific Cryostat TN60 Operating Instructions Manual page 33

9.4 AUTOMATIC/MANUAL DEFROST
For optimum performance of the cooling unit a low thermal contact resistance at the
cooling lamella is required. Upon frequent use of the instrument moisture will
condensate and freeze on the surface of the cooling lamella and increase the thermal
contact resistance. To avoid further build-up of the ice film, automatic defrosting cycles
can be performed.
During an automatic defrost or a manual activated defrost hot gas from the cooling
system is pressed through the evaporator. All ice which has built up is melted, the water
drops into a heated tray below of the evaporator and from there it flows into a tray with
hot tubes and evaporates inside the instrument.
The defrost will last till the system reaches a temperature of +20°C on the evaporator.
The temperature inside the chamber is still below 0°C so that samples can be left on the
cooling bar.
The default setting for automatic defrost is set to 00:00 o'clock
i
(midnight) each day. For changing the settings, please refer to section
7.3.
Always keep the front cover closed during the process.
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