adjusted by rotating the screwdriver.
•
Only one potentiometer covers all functions -
adjustments are stored by the instrument.
•
Potentiometer is only active while small button
is held down.
•
If the potentiometer is turned to one of its end
stops, the reading continues to advance in the
relevant direction until backed off. It is
advisable to set the pot back to its central
position after releasing the small button in
readiness for the next adjustment.
8.3 Zeroing
The reading cannot be adjusted until the digits
stop flashing. This is to allow the sensor to
stabilise after energising. A ‘short-cut’ zero is
provided by pressing the large button whilst the
small button is held down in zero mode. Only
perform this operation in fresh air.
Note: The zeroing facility is not provided on
oxygen units as the reading should be calibrated
to 20.9% in fresh air.
8.4 Calibration
As with zeroing, the reading will flash until the
sensor has stabilised. Additionally, time must be
allowed for the reading to level off once
calibration gas has been applied. The final
reading can then be adjusted. A ‘short-cut’
calibration to 20.9% on oxygen units is provided
by pressing the large button whilst the small
button is held down in calibrate mode.
Gasman II
Instruction Manual
Issue 5
Page 20
11/99
