Uson 628 - Leak Test Cycle

Introduction 2-9
2.4.2 Leak Test Cycle
A leak test cycle consists of the following steps, which are controlled by the
parameters of the selected program:
*Note: At the start of the vent phase, if the Couple output is enabled, a safety check is performed to check that
the minimum safe pressure level is reached before releasing the output.
Figure 2–4: Valve Timing
ID Test Step Description
1 Couple
Pressurizes the couple port on the rear panel and can be
used to activate external devices (e.g., optional auto-
coupler). The Couple phase time must be set to allow the
external device to operate prior to the test component
being Pressurized. The Couple output is maintained for
the duration of the test. If a Couple Phase is set, an equal
Uncouple time is set after the test phase.
2 Auto Zero Vents the sensors to atmosphere and updates zero.
3 Fill and Fill 2
The Fill/Vent Valve changes to position A to pressurize
the test component to the preset test pressure.
4 Stabilize
The Fill/Vent Valve changes to position B to isolate the
test component from the test pressure and allows the
pressure within the test component to Stabilize for a
preprogrammed time.
5 Equal
A fixed 0.3 s delay to allow the equalization valve to
change to position B to isolate the test and reference port.
6 Measure
During this phase, the instrument compares the
pressures at the test and reference ports. The test fails if
the pressure drop between the two ports is outside a
programmed tolerance. The test result is indicated on the
display, the result outputs and information is logged when
enabled.
7Vent*
The Fill/Vent Valve changes to position C and the
Equalization Valve changes to position A. The test
pressure is vented and the display returns to Ready.
8 Uncouple The external couple device is released.