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control equipment display reads zero.
Calibrating the detector
8. Apply calibration gas (which should either be 100% volume target gas,
or be a representative mix of the required range, for example 60%
CH4 / 40% CO2) to the detector at a flow rate of 0.5 1 litre/minute
via a flow adaptor
(Part No. C03005)
. Contact Crowcon for the supply
of calibration gas.
9. Allow the gas reading to stabilise (usually 30 to 60 seconds) and adjust
the ‘CAL’ pot until the DVM reads the appropriate reading (200mV if
100% volume target gas is used). Use the following formula to
calculate the DVM reading if the target gas concentration in the
calibration gas is lower than 100% volume:
(
160
Range
x Gas
)
+ 40 = mV setting
Where the ‘Range’ is the maximum value of the target gas, and ‘Gas’ is
the concentration of the target gas in the calibration mixture.
Example: calibrating a detector to measure 0100% volume methane in
carbon dioxide, using 60% CH4 / 40% CO2 calibration gas:
(
160
100
x 60
)
+ 40 = 136 mV
10.If the control equipment display requires adjustment consult the
operating manual for the equipment.
11..Remove the gas and allow the sensor to completely settle before re
checking the zero setting.
12.Close the junction box of the detector ensuring that the lid is securely
tightened, and the grubscrew is secured.
13.The detector is now operational.
Note:
Xgard
Type 6 will only measure reliably when exposed to a gas
mixture for which it is calibrated. If, for example, a detector is
calibrated for a CH4 / CO2 mixture, but exposed to air, erroneous
signals will be produced.
3. Operation
Xgard Type 6
