Agilent Technologies G8610A Operation Manual page 73

Agilent Technologies Helium Leak Detector
Auto-Zero<0 Active
Auto-Zero < 0 Inactive When Auto-Zero < 0 is inactive, the leak detector does not
NOTE
Gross Test
Adjusts the zero reference point automatically and continually to
the correct zero value when the helium background level drops
below the previously set zero reference point. This feature ensures
that the leak detector maintains a correct balance value after a pre-
viously zeroed background signal naturally cleans up (background
helium is pumped away).
When the Auto-Zero < 0 feature is in the process of re-adjusting
the zero reference point, the arrows located on the left end of the
bar graph illuminate. These arrows indicate that the measured
helium leak rate is currently less than the minimum displayable
value. The arrows may flash briefly as the system recovers from a
leak indication and the displayable leak rate approaches zero. If
the Auto-Zero < 0 is turned on, the arrows may also flash briefly as
the system resets the zero point to a lower value. The leak detector
does not display a leak rate while the arrows are on. If the arrows
remain on for more than a few seconds, press Zero to set operating
parameters to the correct zero value. This situation can occur if the
leak detector had not been fully warmed up when a previous cali-
bration was initiated.
automatically adjust the zero reference point when the helium
background level drops below the previously set zero reference
point. In this condition, a leak less than the previously set zero
value is not indicated by the system. Instead, the arrows remain lit,
indicating that the background level is below the previously set
zero reference point. Press Zero on the front panel to readjust the
zero reference point manually. This clears the lights.
For High Pressure Test/Sniffing mode, de-activation (Inactive
AZ<0) is highly recommended. Manual Zeroing produces a
more desirable performance, thus eliminating false leaks due to
fluctuations in test port pressure while in test.
Allows the operator to locate leaks while the system is in roughing
mode. The test indicates the presence of a leak at high pressures
only and does not display a leak rate value.
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