Detcon DM-434B - Manual (Page 10)

7.2 Calibration
1) Declassify the area around the sensor.
2) Remove the junction box cover.
3) Measure the voltage between signal test points. If necessary, adjust the “fine” and/or “coarse” span
potentiometer(s) to achieve a reading of 174 mV DC.
4) If applicable, remove the rain shield or splash guard from the sensor housing.
5) Attach the calibration adapter to the threaded sensor housing.
6) Apply the test gas at a controlled flow rate of 500 ml/min. Wait 2-3 minutes for signal stability.
7) Use the “zero” potentiometer to adjust the signal to a reading of 40 mV DC.
8) Remove the gas standard and calibration adapter. Observe that the signal increases back to 174 mV DC
within 3-5 minutes. Make any needed adjustments to the “fine” and/or “coarse” span potentiometer.
Note: Because there is interaction between the span and zero functions, it may be necessary to repeat steps 5 through 8.
Calibration is complete. Replace the rain shield and junction box cover.
7.3 Calibration Notes
Detcon Model DM-434B sensors provide a signal output of 4-20 mA DC which corresponds to 0-25% O2.
This signal is reflected by a 40-200 mV DC voltage across the signal test points. Thus, every 1% change in
oxygen concentration will be reflected by a 6.4 mv DC change in the signal as measured across the signal
test points.
7.4 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. Records should be kept. Less frequent test schedules should be imple-
mented based on analysis of tests prior to adjustment.
8.0 SPARE PARTS LIST
613-010000-000 Sensor rain shield
613-120000-000 Sensor splash guard
943-000006-132 Threaded Calibration Adapter
897-850400-000 NEMA 7 enclosure cover
897-850800-000 NEMA 7 enclosure less cover - 3 port
897-850700-000 NEMA 7 enclosure cover with glass lens
960-202200-000 Condensation prevention packet (replace annually).
370-399100-000 Plug in replacement O2 sensor cell
399-200000-000 Stainless steel sensor housing assembly (does not include plug in sensor)
500-005065-034 Connector board
925-345400-025 Plug in control circuit
330-X50000-000 Oxygen field replaceable plug-in sensor
Detcon Model DM-434B Oxygen Sensor PG.10