Detcon FP-624C - Manual (Page 18)

a) Verify the current calibration gas level setting as indicated by the programming status menu. To do this, follow
the instructions in section 3.9 and make note of the setting found in listing number 14. The item appears as
“CalLevel @ xx%”.
b) If the calibration gas level setting is equal to your calibration span gas concentration, proceed to item “f”. If
not, adjust the calibration gas level setting so that it is equal to your calibration span gas concentration, as
instructed in items “c” through “e”.
c) Enter the programming menu by holding the programming magnet stationary over “PGM 2” for 30 seconds
until the display reads “VIEW PROG STATUS”, then withdraw the magnet. At this point you can scroll
through the programming menu by momentarily waving the programming magnet over “PGM 1” or “PGM 2”.
The menu options are: View Program Status, Set Alarm 1 Level, Set Alarm 2 Level, Set Gas Factor, Set Cal
Factor, and Set Cal Level.
d) From the programming menu scroll to the calibration level listing. The menu item appears as: “SET CAL
LEVEL”. Enter the menu by holding the programming magnet stationary over “PGM 1” for 3 seconds until
the display reads
“CalLevel @ ##%”, then withdraw the magnet. Use the programming magnet to make an
adjustment to “PGM 1” to increase or “PGM 2” to decrease the display reading until the reading is equal to the
desired calibration span gas concentration. Save value by holding the programming magnet over “PGM1” for 3
seconds.
e) Exit back to normal operation by holding the programming magnet over “PGM 2” for 3 seconds, or automati-
cally return to normal operation in 30 seconds.
f) From the calibration menu “1-ZERO 2-SPAN” (section 3.8.1-a) proceed into the span adjust function by
holding the programming magnet stationary over “PGM 2” for 3 seconds until the display reads “APPLY
xx% LEL” then withdraw the programming magnet. The x’s here indication the gas concentration requested.
g) Apply the calibration gas at a f low rate of 200 milliliters per minute. As the sensor signal changes, the display
will change to “SPAN XX%”. The “XX” part of the reading indicates the actual gas reading which will increase
until the sensor stabilizes. When the sensor signal is stable it will auto span to the request concentration and
the display will change to “SPAN COMPLETE” for two seconds and then “REMOVE GAS”. Remove the
gas. When the signal level has fallen below 10% of full scale, the display will return to the normal operation
menu, “0 % LEL”.
NOTE 1: If the circuitry is unable to adjust the span to the proper setting the sensor will enter into the calibra-
tion fault mode which will cause the display to alternate between the sensor’s current status reading and the cal-
ibration fault screen which appears as: “CAL FAULT” (see section 3.8.3).
NOTE 2: If, after entering the span function, more than one minute elapses before calibration gas is applied,
the sensor will enter the calibration fault mode which will cause the display to alternate between the sensor’s
current status reading and the calibration fault screen which appears as: “CAL FAULT” (see section 3.8.3).
Span calibration is complete.
3.8.3 Additional Notes
1. Upon entering the calibration menu, the 4-20 mA signal drops to 2 mA and is held at this level until you
return to normal operation.
2. If during calibration the sensor circuitry is unable to attain the proper adjustment for zero or span, the sensor will
enter into the calibration fault mode which will activate fault alarm functions (see section 3.11) and cause the dis-
play to alternate between the sensor’s current status reading and the calibration fault screen which appears as:
“CAL FAULT”. If this occurs you may attempt to recalibrate by entering the calibration menu as described in
section 3.8.1-a. If the sensor fails again, defer to technical trouble shooting.
3.8.4 Calibration Frequency
In most applications, monthly to quarterly calibration intervals will assure reliable detection. However, industrial
environments differ. Upon initial installation and commissioning, close frequency tests should be performed, weekly
to monthly. Test results should be recorded and reviewed to determine a suitable calibration interval.
Model FP-624C Combustible Gas Sensor PG.18