40
Use a concentration of certified gas that is in the range required for your application. The gas ordered
should be a mixture of the gas desired with a balance of nitrogen (N
2
), i.e. 100 ppm NO bal N
2
. Your
gas bottle should have a pressure regulator that can be adjusted to the 30 psi range.
6.6 CALIBRATING THE DRAFT SENSOR
The Draft Reading indicates the internal stack pressure in water gauge column inches or hPa. The
figure represents a differential pressure between the stack pressure and the ambient pressure. It
enables the flow rate of the chimney/stack to be determined.
The Draft sensor is pre-calibrated at the factory. If however the sensor requires re-calibration the fol-
lowing procedure must be adhered to.
1.
Connect the probe
2.
Go to 'Manual Cal' in the main menu.
3.
Select 'Draft zero'. Since the probe is of ambient pressure, press 'Cal' then 'Exit'.
4.
Select 'Draft span'.
5.
Arrange for a calibration pressure to be applied to the probe inlet. This is done in the factory as
illustrated below.
6.
Dial in the calibration pressure. Press 'Enter'. Press 'Cal' when ready.
6.7
REPLACING GAS SENSORS
Unplug the unit from the power supply
Replacement of gas sensors is extremely simple. Undo the 2 back panel retaining screws and remove
the panel. (Spare calibrated sensors may be quickly substituted).
The oxygen sensor is a bayonet fitting. Replacement is made by simply unplugging the old sensor
and replacing with a new one. The replacement Oxygen sensor does not require calibration.
All other gas sensors are replaced by removing the 3 retaining screws, removing the old sensor and
replacing with a new pre-calibrated one-securing with the same 3 screws and replacing the back
panel. The connectors from the sensors must be attached to the relevant 'CONN' position. See dia-
gram below for 'CONN' positions for each sensor.
FIRETRON
®
ANALYZERS
F1
F2
F3
F4
ON
STANDBY
SERVICE
CHARGE
LOW BATT
FAULT
ENTER
PROBE
Flue Gas
Draft
Exhaust
1
2
Hold 2secs.
On/Off
Calibrated Monometer
Squeeze bulb
