Page 90
Pressure Decay Test
How PD Works
1. The operator connects a product to the test port and pushes the START
switch. Or the start could be activated by automated equipment.
Information about input and output connections is on page 86.
2. If external fixtures are used to seal the product, the coupling timer
provides delay time needed to activate the fixture before starting the test.
A coupling valve can be used to supply air to the fixture and hold
pressure until the test ends. Set to zero if no coupling time is needed.
3. At the end of coupling time, the pressure decay valve opens and fills the
product with air. Sprint LC goes into the stabilize phase only if test
pressure is within the pressure error tolerance at the end of the fill phase.
4. At the end of fill time, valves close trapping air inside the product
(including the the internal test circuit.) Stabilization time lets the
pressurized product settle before Sprint LC starts taking pressure drop
readings. This lessens the effects of expansion and contraction on large
or flexible products. If the product is very small and made of rigid
material, the stabilization time can be set very low.
5. At the end of stabilization time, Sprint LC starts looking for a drop in
pressure from the stabilized pressure. Sprint LC goes into test phase only
if test pressure is within the pressure error tolerance at the end of the
stabilize phase.
6. During test time, Sprint LC compares the actual pressure drop to the
reject level. IF the pressure decay (or pressure loss) is equal to or less
than the reject level at the end of test time, the pass indicator lights up.
The fail light turns on if the pressure is beyond the reject level. Pass and
Reject lights go out after 30 seconds, or cleared immediately if another
test is started. Messages in the status box stay on until the next test.
7. If the dump parameter is set to auto or a time, the dump valve vents the
product to atmosphere and the coupling valve turns off. If another test is
linked to the pressure decay test, Sprint LC goes to the next linked test in
the series as long as the product passed all tests.
8. At the end of all linked tests, the operator (or automated machinery)
removes the product and Sprint LC is ready to begin the next test.
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