Detcon FP-624D - Manual (Page 21)

Model FP-624D
FP-624D Instruction Manual Rev. 1.2 Page 17 of 42
c) The transmitter 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.
3.4.2 AutoSpan
Material Requirements:
-Detcon PN 327-000000-000 MicroSafe™ Programming Magnet
- Detcon PN 613-120000-000 Splash Guard with integral Cal Port -OR-
-Detcon PN 943-000006-132 Threaded Calibration Adapter
-Detcon PN 942-520124-050 50% LEL Methane in balance air (recommended) or other suitable span gas
containing a certified level of % LEL concentration of combustible gas in air balance. A flow fixed rate of
200-500cc/min is recommended.
NOTE 1: Before performing AutoSpan Calibration, verify that the AutoSpan level matches
the span calibration gas concentration as described in Section 3.5.2 Set AutoSpan Level.
NOTE 2: The span gas source must have a normal background concentration of 20.9% O2.
Pure Nitrogen background mixtures are not acceptable!
Significant span calibration
inaccuracies will result.
NOTE 3: If the target gas is other than methane, use the appropriate Gas Factor as described
in Section 3.5.3 Set Gas Factor
NOTE 5: To maintain the CSA certification, it must be calibrated on methane.
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. This concentration must be equal to the
calibration gas level setting. The factory default setting and recommendation for span gas concentration is
50% LEL. If a span gas containing the recommended concentration is not available, other concentrations may
be used as long as they fall between 5% and 95% LEL. However, any alternate span gas concentration value
must be programmed via the “Set AutoSpan Level” menu before proceeding with AutoSpan calibration.
Follow the instructions “a” through “e” below for AutoSpan calibration.
a) Verify that the AutoSpan Level is equal to the calibration span gas concentration. (Refer to View Sensor
Status in Section 3.5.1.) If the AutoSpan Level is not equal to the calibration span gas concentration,
adjust the AutoSpan Level as instructed in Section 3.5.2 Set AutoSpan Level.
b) From Normal Operation, enter Calibration Mode by holding the programming magnet over PGM1 for 3-4
seconds. Note, the “▲” prompt will show that the magnetic switch is activated during the 3-4 second hold
period. The display will then scroll “PGM1=Zero…PGM2=Span”. Hold the programming magnet over
PGM2 for 3-4 seconds once the “▼” prompt appears, until the display starts to scroll “Span Cal” to
execute AutoSpan (or allow to timeout in 5 seconds if AutoSpan is not desired). The display will then
scroll “Apply XX % LEL” (where XX is the AutoSpan Level).
NOTE: Upon entering Calibration Mode, the 4-20mA signal drops to 2mA and is held at this
level until the program returns to normal operation. The “In Calibration” bit in the Modbus
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