Agilent Technologies VS Series Operation Manual page 65

VS Series Helium Mass Spectrometer Leak Detectors
Audio Volume
Hold
Calibrate
Adjusts the volume up and down by pressing on the +/- buttons:
When the leak rate bar graph display is set to Linear mode:
❑
The audio signal increases from a low to high frequency
❑
as the leak rate increases within each decade.
The pitch cycles low to high as it passes through each
❑
decade. The audio response corresponds directly to the
size of the leak.
To turn the sound on/off, press the speaker button. The
❑
volume level is restored to the level it was at prior to being
turned off.
Places the system in Hold; keeps the test port under vacuum and
does not vent. Use Hold to keep the system under vacuum, while
taking the leak detector out of test. This is useful if you want to let
the leak detector clean up the helium background, while keeping
the system under vacuum.
Press Hold while the leak detector is in the test state and the unit
advances to the Hold state. When in Hold mode, the test port is
isolated from the leak detector vacuum system. Since the test port
pressure gauge is located on the test port side of the isolation valve,
a subsequent rise in test pressure can be observed while in this
mode.
Calibrates the system. Internal or External appears to indicate
which leak the system is using to calibrate.
Automated calibration is performed based on the parameters set on
the Calibration Set-Up screen (Section 2.2.4.1 "Calibration Set-Up"
on page 2-17). The Calibrate LED lights while calibration is taking
place.
The sequence of events is:
The leak detector exposes the internal standard leak to the
❑
system or verifies that the test port is roughed out and
exposes the external leak to the system.
The ion voltage is scanned to find the peak signal.
❑
The system notes the leak rate reading, turns the leak off and
❑
zeroes the system.
A gain is calculated from the leak rate reading to make the
❑
signal match the value of the calibrated leak and returns the
system to Test mode.
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