G F M 4 0 0 S E R I E S U S E R M A N U A L
Gas
Span set point
%CH
4
60%
WARNING FLAMMABLE
%CO
2
40%
WARNING ASPHIXIANT
%O
2
21%
ppm H
2
S
1500ppm
WARNING TOXIC
ppm CO
1000ppm
WARNING TOXIC
NOTE: Only attempt to calibrate at the span point if the current gas
reading is /- 5% of the indicated span gas point. If ‘calibrate’ does
not appear in the lower centre of the screen, this means that it is not
possible to calibrate at the span point under that set of circumstances.
Connect a cylinder
of the appropriate
gas at the specified
concentration to
the instrument.
DO NOT
connect the gas
cylinder direct to
the instrument
because this will
cause irreparable
damage. Instead, connect through a ‘T’ piece to bypass most of the gas to
exhaust.
Now press the ‘calibrate’ key.
Auto zero
The Auto zero feature is a quick calibration option which automatically zeros all gas
channels. We recommend the Auto zero is used no more than twice in one day.
First switch the instrument on. This
will show the start-up banner.
Press the ‘auto zero’ key. This will start
the automatic zero process. The
screen will show a countdown during
which the instrument is purged of all
traces of gas before zeroing the gas
channels.
GFM400 Series
21
GFM400 Series User Manual
