Chapter 7: Troubleshooting
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If vacuum problems continue, consider obtaining a second vacuum gauge
capable of reading a vacuum of 0.010 mBar. It is often useful in determining
if the vacuum pump is operating properly and the vacuum sensor reading is
accurate.
4.
Isolate the pump by disconnecting the vacuum hose from the freeze
dry system. Deadhead the pump by inserting the vacuum sensor from
a secondary vacuum gauge into the end of the vacuum hose and
observe the vacuum reading obtained. Confirm that the pump is
capable of achieving an ultimate vacuum less than 0.010 mBar or
approximately 10 microns. If an inadequate vacuum reading is
obtained, the pump has most likely failed and may need to be replaced
or rebuilt.
Gaskets, Tubing, Connections and Sample
Valves
1.
Check all sample valves on the side of the cabinet and ensure all
valves are closed or in the vent position.
2.
Check all vacuum tubing for signs of deterioration or cracking.
3.
Check all connections and make sure they are secure and leak tight.
4.
Check the freeze dry system door gasket for indentations cracks or
tears. Clean gaskets using a soft, lint free cloth or paper towel.
5.
The freeze dry system chamber and collector must be dry.
6.
When checking the sample valves, pull as much vacuum as possible.
If a vacuum indication is displayed, wiggle or rotate the valves and
watch the gauge for any fluctuation. Fluctuations can show a
potential vacuum leak. If the valve seems to be in good condition,
remove the valve and apply a thin coat of vacuum grease to the stem
and the outside sealing surface of the valve body, and reinstall the
valve. If the valve still seems to be the source of the problem, remove
the valve and stopper the hole with a rubber stopper. Continue
checking the other valves.
