Operating Manual Freeze Dryer
ALPHA 1-4 LD-2 / 2-4 LD-2
, Version 0203, Page 42
7
Error Correction
7.1
Power Failure
In the event of a power failure during the drying process the batch may become
unusable. Whether the batch can be saved depends on the drying phase in which the
product was when the power failure occurred.
It is important to distinguish between the main drying and final drying phase:
The product is in the final drying phase when the residual moisture has reached
approx. 5 %. Below this value the product is generally not damaged in the event of a
power failure.
If the product is in the main drying phase we recommend that the unit is vented, the
product taken out and stored in a deep-freeze. Before further operation the defrosted
condensate must be drained.
7.2
Insufficient Vacuum
Special attention must be paid to the high-vacuum valves. The defrosting water valve
as well as the rubber valves must be checked.
We recommend that after disconnecting the mains plug the left side panel of the unit is
unscrewed and then the hose inside the unit is detached from the defrosting water
valve, the pipe connection is sealed with a rubber stopper, and the unit evacuated. If
the unit will now reach the necessary operating pressure there is a leakage in the
valve. This is caused by residues from the drying process, fluff from cleaning cloths or
wear and tear of the O-rings of the valves.
To eliminate this fault we recommend that the unit is evacuated and vented by means
of the defrosting water valve so that any residue is removed. If necessary, the O-rings
must be replaced.
The next step is to check all the small flange connections between the freeze dryer
and the vacuum pump and especially the position of the centering rings. It is usually
not necessary to grease the sealing rings with high vacuum grease. If so, then use
very little!
If the leakage cannot be eliminated in this way, the manual valve must be cleaned or
replaced.
Check the oil level in the vacuum pump, change oil if dirty, carry out pressure test.
Check if the whole surface of the ground-in socket of the acrylic chamber has been
greased evenly with vacuum grease.
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