Detcon CXT-IR - Manual (Page 24)

Model CXT-IR
NOTE
The "
◄" prompt will show that the magnetic switch is activated during the 3 second hold
period.
NOTE
Upon entering calibration mode, the Modbus™ status register bit 14 is set to signify the
sensor is in-calibration mode. This bit will remain set until the program returns to normal
operation.
c) The ITM will display the following sequence of text messages as it proceeds through the AutoZero
sequence:
Zero Cal . . . Setting Zero . . . Zero Saved (each will scroll twice)
d) Remove the zero gas and calibration adapter, if applicable.
3.3.2 AutoSpan
The AutoSpan function is used to span calibrate the sensor. AutoSpan should be performed periodically or as
required. AutoSpan should be considered after periods of over-range target gas exposure. Unless otherwise
specified, span adjustment is recommended at 50% of range. This function is called AUTO SPAN.
NOTE
Before performing AutoSpan calibration, verify that the AutoSpan level matches the span
calibration gas concentration as described in Section3.4.3 Set AutoSpan level.
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 Span Gas. Recommended span gas is 50% of range with target gas. Other suitable span gas
sources containing the target gas in air or N2 balance are acceptable.
NOTE 1 Contact Detcon for ordering information on span gas cylinders.
NOTE 2
A target gas concentration of 50% of range is strongly recommended. This should be
supplied at a controlled flow rate of 200 to 500cc/min, with 500cc/min being the
recommended flow rate. Other concentrations can be used if they fall within allowable
levels of 5% to 100% of range.
NOTE 3
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.
NOTE 4
It is generally not advised to use other gasses to cross-calibrate for span. Cross-calibration
by use of other gasses should be confirmed by Detcon.
CAUTION
Verification that the calibration gas level setting matches the calibration span gas
concentration is required before executing AutoSpan calibration. These two
numbers must be equal.
AutoSpan consists of entering calibration mode and following the menu-displayed instructions. The display
will ask for the application of span gas in a specific concentration. The applied gas concentration must be
equal to the calibration gas level setting. The factory default setting and recommendation for span gas
CXT-IR Instruction Manual Rev. 1.6 Page 20 of 44