Model 979 Series Helium Mass Spectrometer Leak Detector
DRAFT 9/15/03
3-3
3.1.1 Manual Zeroing and Calibrate
Touch the MANUAL ZEROING and CALIBRATE box to display the Manual Zeroing and Cal
screen (Figure 3-4), which provides control over the leak detector AUTO-ZERO < 0 feature
and allows for viewing and adjusting the spectrometer tube Gain.
Figure 3-4
Manual Zeroing and Cal Screen
3.1.1.1 AUTO-ZERO < 0
Touch the AUTO-ZERO < 0 toggle box to switch the Auto Zero < 0 feature between Active
and Inactive. The display in the touch screen box indicates the current setting.
ACTIVE
AUTO-ZERO < 0, when activated, automatically adjusts the zero
reference point back up to zero when the helium background level
drops below the previously set zero reference point. This feature
ensures that the leak detector maintains calibration after a previ-
ously zeroed background signal naturally cleans up.
When the AUTO-ZERO < 0 feature is in the process of re-adjusting the zero reference point,
the UNDER light indicator located on the left end of the bar graph illuminates. This light
indicates that the measured helium leak rate is currently less than the minimum displayable
value. The light may flash briefly as the system recovers from a leak indication and the dis-
playable leak rate approaches zero. If the AUTO-ZERO < 0 is turned on, the UNDER light
may also flash briefly as the system resets the zero point to a lower value. The 979 does not
display a leak rate while the UNDER light is on. If this light stays on for more than a few sec-
onds, recalibrate the system to set operating parameters to the correct zero value. This situa-
tion can take place if the 979 had not been fully warmed up before a previous calibration
was initiated.
INACTIVE
When AUTO-ZERO < 0 is inactive, the leak detector does not
automatically adjust the zero reference point back up to zero
when the helium background level drops below the previously set
zero reference point. When this occurs, the UNDER light remains
lit, indicating that the background level is below the previously set
zero reference point. Press the ZERO button on the front panel to
readjust the zero reference point manually. This clears the UNDER
light indication.
MANUAL ZEROING AND CAL
AUTO-ZERO <0
ACTIVE
GAIN:
X.X
ESC
DONE
DN
UP
NXT
OFFSET:
XX
BACK
MANUAL
ZEROING &
CALIBRATE
MANUAL
SPEC TUBE
TUNING
MANUAL
VALVE
CONTROL
SYSTEM
INIT
SET-UP
GAUGE
CAL
Содержание 979 Series
Страница 12: ...Model 979 Series Helium Mass Spectrometer Leak Detector This page intentionally left blank D R A F T 9 1 5 0 3 ...
Страница 112: ...Model 979 Series Helium Mass Spectrometer Leak Detector This page intentionally left blank D R A F T 9 1 5 0 3 ...
Страница 132: ...Model 979 Series Helium Mass Spectrometer Leak Detector This page intentionally left blank D R A F T 9 1 5 0 3 ...
Страница 138: ...Model 979 Series Helium Mass Spectrometer Leak Detector This page intentionally left blank D R A F T 9 1 5 0 3 ...
Страница 139: ......