Labconco FreeZone Stoppering Tray Dryers 79480 Series - Manual (Page 43)

Chapter 7: Troubleshooting
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3.
If bubbling is observed around the bulkhead fittings, access the bottom of
the chamber and remove the insulation. Tighten the appropriate fitting by
placing a wrench on the fitting inside the chamber and use a second
wrench to turn the nut on the bottom of the chamber. Be careful not to
damage the evaporator coils or the brazed joints to the refrigeration
system. Once the fitting is tightened, perform the test again. Should the
bubbling still be present, loosen the bulkhead fittings and apply vacuum
grease to the O-rings, then reassemble and test.
4.
If bubbling was observed on the chamber surface, the chamber must be
replaced. This type of leak cannot be successfully repaired. The leading
cause of a chamber surface leak is corrosive residue left in the chamber
after use.
This test verifies that the vacuum leak is in the Stoppering Tray Dryer.
1.
Remove the Stoppering Tray Dryer.
2.
Position a flat gasket over the 3.0 inch diameter vacuum port and turn a
large freeze dry flask upside down to cover the connection port.
3.
Start the freeze dryer and observe the vacuum indication. If the vacuum
indication is good, then the problem is in the Stoppering Tray Dryer and
you should proceed to Section IV, Stoppering Tray Dryer.