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Vacuum Testing
Parameters in a vacuum test are identical to a pressure decay test. Your
vacuum tester may have an internal vacuum venturi installed to generate
the vacuum for testing small parts. If a vacuum venturi is installed, an
external air pressure regulator will be included on the back used to
establish the desired vacuum level. If the tester has the vacuum only, then
the vacuum regulator is installed in the position normally occupied by the
positive pressure regulator in a standard machine.
Programming a vacuum test is not specifically covered in this guide, but
follow the same steps as are listed for a pressure decay test.
Vacuum Venturi Generator
An internal venturi vacuum generator is typically installed in the tester to
provide the negative pressure necessary. The venturi converts positive air
pressure to negative air pressure. The vacuum test pressure is set in the
same manner as positive pressure.
The vacuum is controlled by adjusting the positive pressure regulator that
supplies the venturi. If only vacuum tests are available on Sprint LC, the
vacuum regulator is located in the same place as the positive pressure
regulator would be. If Sprint LC has both positive and vacuum tests
available, a second regulator is provided on the back of Sprint LC. The
vacuum level is set by adjusting this regulator on the back of Sprint LC.
A venturi is best for test applications in which extreme vacuum levels are
not needed (typically lower than 25 inches of mercury or 12.3 psig
vacuum) and where the product volume is not particularly large. If the
product under test has an internal volume greater than one or two liters, it
may be advantageous to use an external vacuum pump instead of the
venturi vacuum.
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