Detcon CXT-IR - Manual (Page 23)

Model CXT-IR
3.2 Normal Operation
In normal operation, the ITM Display will be blank and will display the gas reading once every 10 seconds for
about 2 seconds (normally appear as 0). At any time swiping a magnet across either PGM1 or PGM2 will
cause the ITM to display the units and gas type (i.e. % LEL or PPM H2S). If the sensor is actively
experiencing any diagnostic faults, a swipe of the magnet will cause the display to scroll the fault condition.
Refer to Section 3.5for more information on fault conditions.
3.3 Calibration Mode
Zero and span calibration should be performed on a routine basis (quarterly minimum is advised) to ensure
reliable performance. If a sensor has been exposed to any de-sensitizing gases, or to very high over-range
combustible gas levels, re-calibration should be considered. Unless otherwise specified, span adjustment is
recommended at 50% of the full scale range.
To enter Calibration Mode hold the magnet over PGM1 for 3 seconds. If the sensor is experiencing a fault
condition the "
◄" prompt will not appear until the fault(s) have been displayed. When the ITM enters
Calibration Mode the display will scroll Pgm1=Zero . . . Pgm2=Span twice before returning to Normal Mode
(about 5 seconds).
3.3.1 AutoZero
The AutoZero function is used to zero the sensor. AutoZero should be performed periodically or as required.
AutoZero should be considered after periods of over-range target gas exposure. Local ambient air can be used
to zero calibrate a combustible gas sensor as long as it can be confirmed that it contains no target or
interference gasses. If this cannot be confirmed then a zero air or N
2
cylinder should be used.
Material Requirements:
• DetconMicroSafe™ Programming Magnet (PN 327-000000-000)
• Detcon Splash Guard with integral Cal Port (PN 613-120000-700) and Calibration Wind Guard (PN
613-120000-700) -OR-
• Detcon Threaded Calibration Adapter (PN 943-000006-132)
• Detcon Zero Air cal gas (PN 942-001123-000) (or use ambient air if no target gas is present)
• Detcon Nitrogen 99.99% (PN 942-640023-100)
NOTE
The zero gas source may be zero air or N
2
if local ambient air contains target or interference
gases.
NOTE
The Calibration Wind Guard must be used when the Splashguard Adapter with integral Cal
Port is used. Failure to use the Calibration Wind Guard may result in an inaccurate
AutoZero calibration.
a) For combustible gas sensors, if the ambient air is known to contain no target gas content, then it can be
used for zero calibration. If a zero gas cal cylinder is going to be used, attach the calibration adapter and
set flow rate of 200-500cc/min (500cc/min is the recommended flow rate) and let sensor purge for 1 to 2
minutes before executing the AutoZero.
b) From normal operation, enter calibration mode by holding the programming magnet over PGM1 for 3
seconds The display will then scroll Pgm1=Zero Pgm2=Span. Hold the programming magnet over
PGM1 for 3 seconds once the "
◄" prompt appears to execute AutoZero (or allow to timeout in 5 seconds
if AutoZero is not desired).
CXT-IR Instruction Manual Rev. 1.6 Page 19 of 44