Honeywell Sensepoint XCD, Technical Manual

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Sensepoint XCD Technical Manual SPXCDHMANEN Issue 2
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19. Promptly switch off the calibration span gas and remove the Sensepoint XCD
Gassing Cap from the sensor to allow the gas to disperse.
20. When the reading falls below 50% of the calibration gas level the display indicates a
countdown (up to 180 seconds dependant on gas type).
21. When the countdown is finished, the calibration procedure is complete.
22. The instrument returns to the ‘Set CAL’ menu. Activate the ‘

’ or ‘

’ switch to select
another menu or select ‘QuIT’ to return to normal monitoring mode.
Note: Remember to always replace the Weather Protection and other accessories.
10.2 Zeroing and span calibration of Hydrogen Sulfide sensors
Hydrogen Sulphide sensors can be affected by extreme humidity changes. A sudden
increase in ambient humidity can result in a short-term positive drift in the instrument’s
reading. A sudden decrease in ambient humidity can result in a short-term negative drift in
the instrument’s reading. These are most likely to be noticed during calibration with dry or
cylinder gas.
When calibrating Hydrogen Sulphide cartridges the following should be taken into account
while following the procedure in 10.1:
1. To zero the sensor, use a compressed air cylinder of 20.9%Vol oxygen (not Nitrogen).
Do not use background air.
2. Apply the gas to the sensor for three minutes before using ‘

’ to confirm the zero
calibration.
3. If a span calibration is to be performed, the span calibration gas should be applied to
the sensor immediately after the zeroing procedure. Do not allow the sensor to return
to ambient air conditions between steps 2 and 3.
4. Apply the span gas for two minutes before using ‘

’ to confirm the span calibration.