Detcon TP-524D - Manual (Page 19)

Model TP-524D
TP-524D Instruction Manual Rev. 0.5 Page 15 of 36
concentration is 10ppm for the 0-20ppm range and 25ppm for the 0-50ppm and 0-100ppm ranges. If a span
gas containing the recommended concentration is not available, other concentrations may be used as long as
they fall between 10% and 50% of selected full-scale range. However, any alternate span gas concentration
value must be programmed into the sensor 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
seconds. Note, the “ ” prompt will show that the magnetic switch is activated during the 3 second hold
period. The display will then scroll “PGM1=Exit PGM2=Span”. Hold the programming magnet over
PGM2 for 3 seconds to execute AutoSpan (or allow to timeout in 5 seconds if AutoSpan is not intended).
The display will then scroll “Apply XX ppm Gas”.
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 via the In-Line Humidifying Tube 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 “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 will continue to report a “Range Fault” and will not clear the fault until a successful AutoSpan is
completed.
Assuming acceptable sensor signal change, after 3 minutes 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 sensor reports a “Stability Fault” and returns 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.
If the sensor passes the stability check, the sensor reports a series of messages:
“AutoSpan Complete”
“Sensor Life XXX%”
“Remove Span Gas”
d) Remove the span gas and calibration adapter. The display will report a live reading as the sensor clears
toward “0”. When the reading clears below 8ppm, the sensor will display “Span Complete” and will
revert to normal operation. If the sensor fails to clear to less than 8ppm within 5 minutes, a “Clearing
Fault” will be reported and the sensor will return to normal operation, aborting the AutoSpan sequence.
The sensor will continue to report a “Clearing Fault” and will not clear the fault until a successful
AutoSpan is completed.
e) AutoSpan calibration is complete.
NOTE 1: If the sensor fails the minimum signal change criteria, a “Range Fault” will be
declared and a “Fault Detected” message will be displayed alternately with the sensor’s current
reading. The 4-20mA output will be taken to 0mA.