Models 947, 948 and 960 Leak Detectors Operations and Service Manual
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A Pass condition is indicated by the system reverting to the VENT
mode upon completion of the test cycle. A fail condition results in
REJECT being displayed in the LED display area, and a reject set
point activation upon completion of the test cycle. A Fail condition
is also indicated by the system reverting to the HOLD mode, and
all operating buttons being disabled except VENT. The status of
the reject set points is available at the optional I/O communications
port (host computer) and upon inquiry through the service pendant
(Appendix A, “Service Pendant Keypad Functions”).
Upon the completion of an automated test cycle, the 947/948/960
captures the leak rate signal measured just prior to the end of the
automated test cycle. This leak rate is displayed and held at the
analog output communications port until the next test cycle is initi-
ated. This allows the end user to record the actual leak rate value
for each test object.
ROUGH TIME
The ROUGH TIME variable determines the amount of time that the
leak detector is allowed to evacuate the test object to the tolerable
test transfer pressure. In AUTO SEQUENCER mode, the
947/948/960 transfers into test as soon as the tolerable transfer
pressure is met. It does not wait for the total rough time allotted if it
is not required. If the tolerable test transfer pressure is not achieved
within the pre-selected rough time, the system aborts the cycle and
goes into HOLD mode.
The ROUGH TIME value can be determined empirically and
should reflect the typical time required to rough the test object to
the tolerable test pressure. Failure to achieve the tolerable test pres-
sure within the pre-selected rough time is an indication of a gross
leak in the test object or test fixturing or that the time allowed was
insufficient.
