Detcon DM-100 - Manual (Page 22)

Model DM-100
DM-100 Instruction Manual Rev. 3.3 Page 18 of 40
3. From normal operation, hold the programming magnet over PGM2 for at least 3 seconds. Apply the
span calibration test gas for toxic gas sensors at a flow rate of 200-500cc/min (500cc/min is the
recommended flow rate). The DVM reading will remain at 2mA or "0" for 2 minutes.
4. When the 2 minute wait is complete, the reading will increase to a level that corresponds to the level
of gas the plug-in sensor is detecting. There is a 30 second period to decide if the reading needs to be
adjusted. If the reading matches the level of gas applied continue to Step 7.
5. To adjust the reading, hold the programming magnet over PGM2. The reading will also start to
increase. Continue to hold the programming magnet over PGM2 to make the current increase, or hold
the magnet over PGM1 to make the current decrease. Use PGM1 and PGM2 to adjust the output to
match the target gas set-point. Assuming 50% of full range was applied, adjust the reading to 12mA
(120mV on the DVM).
NOTE
12mA and 50% of full range are based on the use of a span gas concentration of 50%. If a
different concentration of span gas is used, the mA reading will need to be calculated. I.E. if
a 25% concentration span gas is used the reading would be 8mA. Use the magnetic tool to
adjust the mA reading to the target set-point.
6. When the correct adjustment has been made, wait 15 seconds without holding the programming
magnet over either PGM1 or PGM2. The reading will momentarily decrease about 20% and then
return to the target reading. This indicates that the span calibration point has been successfully saved.
If a lack of proper signal level change is internally detected the sensor will immediately go into fault.
The reading will go to 1.2ma (12mV). Only a successful re-calibration will clear this fault (Section 5,
Troubleshooting Guide).
NOTE:
For O2 deficiency sensors, N2 (99.99%) MUST be applied at a flow rate of 500cc/min for
2 to 3 minutes until the sensor reading clears below 2.5% volume O2. At this point the
autospan cycle is complete. If not done properly a clearing fault will occur.
7. Remove the span gas and calibration adapter (or calibration wind guard), or for O
2
deficiency sensors,
apply N
2
at a set flow rate of 500cc/min. On the DVM, the reading will fall from the reported span
level to 4mA (40mV). The sensor now allows 5 minutes for the reading to clear below 10% of full
scale range (5.6mA). If the reading does not meet the clearing test criteria the sensor will go into fault.
The reading will go to 1.2ma 12Mv). Only a successful re-calibration will clear this fault (Section 5,
Troubleshooting Guide).
NOTE:
For O2 deficiency sensors, N2 (99.99%) MUST be applied at a flow rate of 500cc/min for
2 to 3 minutes until the sensor reading clears below 2.5% volume O2. At this point the
autospan cycle is complete. If not done properly a clearing fault will occur.
8. Span calibration is complete. If the Splash Guard was removed for calibration, re-install the Splash
Guard.
NOTE
Any fault during the AutoSpan will cause the current output from the sensor to drop to
1.2mA (12mV).
3.3.2.2 Display Installed
1. Install calibration adapter or wind guard.
2. From Normal Operation, hold the programming magnet over PGM1 for 3 seconds. The display will
scroll 1-ZERO…2-SPAN.