Model 979 Series Helium Mass Spectrometer Leak Detector
2-4
DRAFT 9/15/03
The Audio leak rate indication volume is controlled by the two buttons labeled
HI and LOW and with up and down arrows. Press the HI arrow button to
increase the volume of the tone. Press the LOW arrow button to decrease the
volume of the tone.
When the leak rate bar graph display is set to LINEAR mode (Section 2.7.1
“Units Set-Up” on page 2-28), the audio signal increases from a low to high
pitch as the leak rate increases within each decade. The pitch cycles low to high
as it passes through each decade.
When the leak rate bar graph display is set to LOG mode, the audio signal
increases from a low to high pitch as the leak rate increases through the entire
bar graph scale. The LOG mode display setting is often desirable in sniffer
applications so the audio response corresponds directly to the size of the leak.
The SNIFFER ON/OFF button is used to toggle the 979 leak detector in and out
of SNIFFER mode. The SNIFFER indicator LED illuminates when SNIFFER mode
is enabled.
When the leak detector is in VENT mode, press the SNIFFER ON/OFF
button to start the test cycle. This automatically locks the leak detector into
CONTRA-FLOW™ LEAK mode, auto-ranging through four decades down to the
most sensitive range available for the current leak detector configuration.
If the leak detector is in TEST mode, pressing the SNIFFER ON/OFF button
performs the same function, with the exception of performing the test cycle start
sequence.
When in SNIFFER mode, press the SNIFFER ON/OFF button to switch the leak
detector back into the currently configured normal TEST mode.
Summary of Contents for 979 Series
Page 139: ......
