Detcon FP-100 - Manual (Page 19)

Model FP-100
FP-100 Instruction Manual Rev. 0.0 Page 15 of 30
3.2.2 Span Calibration
Span Calibration is used to adjust the span of the sensor. Span calibration should be performed periodically or
as required. Span calibration should be considered after periods of over-range target gas exposure. Unless
otherwise specified, span adjustment is recommended at 50% of range.
Material Requirements:
-Detcon PN 327-000000-000 MicroSafe™ Programming Magnet
-Detcon PN 613-120000-700 Splash Guard with integral Cal Port with a Wind Guard -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.
-DVM (if a 100 Series Display is not installed)
NOTE: The cover of the junction box will need to be removed if there is not a 100 Series
Display. The area may need to be de-classified.
NOTE: Contact Detcon for Ordering Information on Span Gas cylinders.
NOTE: 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.
Span consists of applying the correct gas concentration at the correct flow rate, and adjusting the sensor for the
proper output. The recommendation for span gas concentration is 50% of range. If a span gas containing the
recommended concentration is not available, other concentrations may be used as long as they fall between
10% and 100% of range.
1. If a 100 Series Display is not installed on the sensor, set a DVM up to measure millivolts, and connect
it across TP1 and TP2 on the terminal board. The DVM will read the voltage drop across a 10Ω
resistor. The resistor develops a 10mV voltage drop per 1mA of current. Thus a reading of 40mV on
the DVM equals 4mA of current. If the sensor has a display, a DVM is not required.
2. Install the Calibration Wind Guard, or the appropriate calibration adapter.
3. From Normal Operation, hold the programming magnet over PGM2 for greater than three seconds.
The display (if connected) will display will flash “CAL” three times and then should display ‘0.0’ and
will flash at a rate of once per second. If a meter is attached, the reading will dip to 2mA (20mV on
the meter).
4. Apply the span calibration test gas for toxic gas sensors at a flow rate of 200-500cc/min (200cc/min is
the recommended flow rate). The DVM reading or display will remain at 2mA for 2 minutes. The
display (if connected) will display the current gas concentration reading.
5. When the 2 minute wait is complete, the mA output will increase to a level that corresponds to the
level of gas the plug-in sensor is detecting. The display (if connected) will flash “ADJ” three times to
indicate the span reading can be adjusted. There is a 30 second period to decide if the reading needs to
be adjusted. If the reading matches the level of gas applied skip to step 7.
6. To adjust the reading, swipe or hold the programming magnet over PGM1 or PGM2. PGM1 is used to
decrease the displayed reading, while PGM2 is used to increase the reading. Short swipes (less than 1