SP Scientific Freezemobile Series, Operator'S Manual, Page: 47 / 54

Rev 005, 02/12 37
© SP Scientific 2012
Appendix
A
Appendix A: Troubleshooting
Vacuum Leak Testing on Research Units
Vacuum leaks can be difficult to locate. By performing the following leak isolation
procedure, you can systematically pinpoint the location of a leak. Once a leak is
discovered, you can either repair it or call SP Scientific Service for assistance.
PRACTICAL OPERATING TIP. SOME UNITS ARE EQUIPPED WITH AN OPTIONAL SODASORB
TRAP. IF THE FILTER CARTRIDGE IS IN THE TRAP, REMOVE IT BEFORE PERFORMING ANY
TESTS. SODASORB WILL ABSORB MOISTURE FROM THE AIR AND CAUSE THE UNIT TO PUMP
DOWN VERY SLOWLY, WHICH MAY AFFECT THE RESULTS OF VACUUM LEAK TESTS.
Testing the Vacuum Pump and Gage
What appears to be a system leak can sometimes be the result of a faulty pump or
gage. Before checking the system for leaks, test the pump and gage to ensure that
they are functioning properly.
The pump can be isolated from the system and tested in a number of different ways.
SP Scientific suggests the following methods:

If the unit is equipped with an optional purge system, activate it. Within a few
minutes of purge system activation, the vacuum display should read 10
millitorr or lower.

If the unit has a smooth wall condenser, plug the ¾” stainless steel tube in the
center of the condenser with either a rubber stopper or a closed Quickseal®
valve. Because this tube connects to the vacuum pump, plugging it can
effectively isolate the vacuum pump from the rest of the system for testing.

If the unit has an internal condenser, the main vacuum hose from the pump
should be clamped off or blocked with a rubber stopper between the vacuum
gage probe and the condenser. This will isolate the pump for testing.
The gage can be tested by attaching a remote calibrated vacuum gage and
comparing the readings for accuracy.
If after performing the above procedures the vacuum fails to drop to an acceptable
range (10 millitorr), the pump or gage may be malfunctioning. If the tests yield normal
results, it is safe to assume that the pump and gage are not the cause of the vacuum
problem.