Detcon FP-524D-HRT - Manual (Page 20)

Model FP-524D-HRT
FP-524D-HRT Instruction Manual Rev. 0.1 Page 16 of 48
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
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.
c) Apply the span calibration test gas at a flow rate of 200-500cc/min (200cc/min is the recommended flow
rate). As the sensor signal begins to increase, the display will switch to reporting a flashing “XX” reading
as the display shows the sensor’s “as found” response to the span gas presented. If it fails to meet the
minimum in-range signal change criteria within 2½ minutes, the display will report “Range Fault” twice
and the sensor will return to normal operation, aborting the AutoSpan sequence. The sensor continue to
report a “Range Fault” and will not clear the fault until a successful AutoSpan is completed.
Assuming acceptable sensor signal change, after 1 minute the reading will auto-adjust to the programmed
AutoSpan level. During the next 30 seconds, the AutoSpan sequence checks the sensor for acceptable reading
stability. If the sensor fails the stability check, the reading is re-adjusted back to the AutoSpan level and the
cycle repeats until the stability check is passed. Up to three additional 30-second stability check periods are
allowed before the unit reports a “Stability Fault” twice and the sensor will return to normal operation,
aborting the AutoSpan sequence. The sensor will continue to report a “Stability Fault” and will not clear the
fault until a successful AutoSpan is completed.