26
Gas Detector CAL Function
Gas detectors must be calibrated with known calibration gases traceable to National Standards. As previously
discussed detectors require regular calibration. Calibration gases should have values chosen that either:
b) Are between 50 to 90% of the range of the detector. The detector measuring range will normally be marked on
the detector.
a) Are at the alarm set point to get maximum accuracy at this point
or
To CAL the detector enter password mode
as previously described and enter
password 100 to enter the user menu.
Select menu item 2 CAL
The top line of the display shows the current
reading. The bottom line shows the current
option.
With CAL gas flowing and the reading stable
press the button to select CONTINUE. Now
press and hold the button until prompted to
release to action the zero request.
CAL
2 of 8
55 PPM
Abort
55 PPM
Continue
CAL
PASSED
50 PPM
CLICK TO
The display shows the result of the cal request, note that the actual zero and
calibration values are stored on the individual detector heads. When carrying out a
zero or calibration the controller sends the request to the detector head for action
and monitors the result. This means that detectors can be supplied pre-calibrated
The reading is now displayed so the result of the cal request can be observed. The
reading should be stable. Click the button to return to the previous menu.
1
sensor
50
BOTTLE
Enter the channel number you wish to
calibrate.
Enter the calibration gas value, this will be
marked on the gas bottle and enter.
Repeat this sequence if you
are not /-2% of the
gas bottle value.
This sequence first indicates
if the zero operation passed
or failed, then the new
detector reading then the
option to end and return to
the engineer menu. This
sequence effectively allows
the engineer to observe the
new detector zero point
before exiting.
Bottled Nitrogen or Instrument grade zero air
Regulator to deliver a
fixed flowrate (typically
between 0.5 to 1 L/min)
Note: the concentration marked on
the label. Ensure it is of the correct
type for the detector being
calibrated. The concentration
should typically be 50 to 90% of
the detector range.
Calibration gas should have a humidity between 0-90%RH
Refer to EN 600179-20-1 for gas concentration guidance.
Calibration gas.
Calibration
Zero
Gas
Gas
20% LEL
