Detcon DM-100 - Manual (Page 21)

Model DM-100
DM-100 Instruction Manual Rev. 3.3 Page 17 of 40
3.3.2 Span Calibration
Span Calibration is used to adjust the span of the sensor and 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 Programming Magnet
 Detcon PN 613-120000-700 700 Series Splash Guard with integral Cal Port and Calibration Wind
Guard (P/N 943-000000-000) -OR-
 Detcon PN 943-000006-132 Threaded Calibration Adapter - OR -
 Detcon PN 943-01747-T05 Teflon Calibration Adapter for highly reactive gases
 Detcon Span Gas (See Detcon for Ordering Information). Recommended span gas is 50% of range
with target gas. Other suitable span gas sources containing the target gas in air or N2 balance are
acceptable.
 DVM (if a loop powered display is not installed)
NOTE 1;
The cover of the junction box will need to be removed if there is not a loop powered
display. The area may need to be de-classified.
NOTE 2:
A target gas concentration of 50% of range is strongly recommended. This should be
applied at a controlled flow rate of 200 to 500cc/min, with 500cc/min being the
recommended flow rate. Other concentrations can be used if they fall within allowable
levels of 10% to 100% of range.
NOTE 3:
The Calibration Wind Guard must be used when the Splashguard Adapter with integral Cal
Port is used.
Failure to use the Calibration Wind Guard may result in an inaccurate
AutoZero calibration.
NOTE 4: Contact Detcon for ordering information on Span Gas cylinders.
NOTE 5:
Ambient air should be used to calibrate O2 deficiency sensors as long as the oxygen
concentration is confirmed to be 20.9%.
NOTE 6:
Cross-calibration for span by use of other gases is not advised and should be confirmed by
Detcon.
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.
3.3.2.1 Display Not Installed
1. 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.
2. Install the Calibration Wind Guard, or the appropriate calibration adapter.