GMI Gasurveyor 500 Series, User Handbook Manual

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2-3
GENERAL INFORMATION
correction techniques are used to minimise drift. The ppm
range includes a manual zeroing procedure.
The ppm range has the option of using a ‘threshold’. By
this, we mean that we can display either a blank screen
or simply a zero (0) on the display, up to a pre-set level.
This allows small readings, which may not be due to the
gas we wish to find or very small amounts of gas, to be
ignored if they fall below any pre-set action levels. This
allows the operator to react only to significant levels.
The ppm range has no threshold set by default. If your
instrument has a threshold, write the level here:
.......................................................................................
The ppm range has the Confidence Audible and Confidence
Visual options active, that is, they will provide assurance
that the instrument is sensing for gas without the need
for the operator to constantly view the display.
The Confidence Audible can be disabled, and the
Confidence Visual can be disabled.
The ppm range has the audible and visual Geiger indication
configured which provides indication of gas concentration
increase via the increased rate of sounder and LED pulse.
The display changes between PPM and Aud as shown in
Figure 2-3.
Figure 2-3 PPM Range