Detcon FP-524D-HRT - Manual (Page 19)

Model FP-524D-HRT
FP-524D-HRT Instruction Manual Rev. 0.1 Page 15 of 48
3.4 Calibration Mode (AutoZero and AutoSpan)
Calibration Mode allows for sensor span calibration. Span calibration should be performed on a routine basis
(quarterly minimum) to ensure reliable performance. If a sensor has been exposed to any de-sensitizing gases
or to very high over-range combustible gas levels, then a re-calibration should be considered.
Unless
otherwise specified, span adjustment is recommended at 50% LEL. This function is called “AUTO SPAN.”
3.4.1 AutoZero
The AutoZero function is used to zero the sensor. Local ambient air can be used to zero calibrate the sensor as
long as it can be confirmed that it contains no combustible gases. If this cannot be confirmed then a zero air
cylinder should be used.
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 942-001123-000 Zero Air cal gas or use ambient air if no combustible gas is present.
NOTE: The zero gas source should have a normal background concentration of 20.9% O2.
Pure Nitrogen gas standards should not be used or errors may result.
a) If the ambient air is known to contain no combustible gas content, then it can be used to zero calibrate. If
a zero gas cal cylinder is going to be used then attach the calibration adapter and set flow rate of 200-
500cc/min and let sensor purge for 1-2 minutes before executing the AutoZero.
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 second hold
period. The display will then scroll “PGM1=Zero …PGM2=Span”. Hold the programming magnet over
PGM1 for 3-4 seconds once the “▲” prompt appears to execute AutoZero (or allow to timeout in 10
seconds if AutoZero is not desired).
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.
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.