Detcon FP-100 - Manual (Page 18)

Model FP-100
FP-100 Instruction Manual Rev. 0.0 Page 14 of 30
3.2 Calibration
Zero and 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, re-calibration should be considered. Unless otherwise specified, span adjustment is recommended
at 50% of the full scale range.
3.2.1 Zero Calibration
Zero Calibration 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 613-120000-700 Splash Guard with integral Cal Port with a Wind Guard -OR-
-Detcon PN 943-000006-132 Threaded Calibration Adapter.
v-Detcon PN 942-001123-000 Zero Air cal gas or use ambient air if no combustible gas is present.
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: 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.
1. If a 100 Series Display is not installed on the sensor, set a DVM to measure millivolts, and connect it
across TP1 and TP2 on the Standard 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 a DVM equals 4mA of current. If the sensor has a display, a DVM is not required.
2. If the ambient air is known to contain no target gas content, then it can be used for zero calibration. If
a zero gas cal cylinder is going to be used, attach the calibration adapter and set flow rate of 200-
500cc/min (200cc/min is the recommended flow rate) and let sensor purge for 1-2 minutes before
zeroing the sensor.
3. From Normal Operation, hold the programming magnet over PGM1 for 3 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 momentarily to 2mA (20mV on the
meter). The reading will then return to 4ma. The ideal reading for zero is 4.03mA (40.3mV on a
DVM).
4. Observe the reading for a minute or so to ensure that the reading does not drift. IF a display is
connected, the display will flash “CAL” three times when it leaves calibration.
5. If zero gas was used, remove the gas from the sensor.