Model 979 Series Helium Mass Spectrometer Leak Detector
2-18
DRAFT 9/15/03
2.6.3.1 Auto Sequencer Set-Up Controls
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 979 trans-
fers 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 your 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 your test object or test fixturing or that time allowed was
insufficient.
TEST TIME
The TEST TIME variable determines the amount of time that the
leak detector remains in test before it compares the measured leak
rate with the selected reject set point. Sufficient time must be
allowed for the leak rate reading to stabilize before the system
makes a pass/fail decision. This is a function of the part configura-
tion and the leak rate specification. In AUTO SEQUENCER mode,
the 979 remains in test for the entire duration of the preselected test
time.
The ON/OFF box located to the right of the TEST TIME box provides the capability to enable
and disable the Auto Sequencer feature.
Summary of Contents for 979 Series
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