Detcon DM-100 - Manual (Page 23)

Model DM-100
DM-100 Instruction Manual Rev. 3.3 Page 19 of 40
3. Hold PGM2 for three seconds and Auto span routine is executed and APPLY XXXXX UUU GGG is
scrolled across the display. Where XXXXX represent the auto span level, UUU represent the units (%
or PPM), and GGG represent the gas type. Output current from the sensor will drop to 3.5mA.
4. 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). As the sensor signal begins to increase the display will switch to XX
reading as the ITM shows the sensor’s "as found" response to the span gas presented. If it fails to meet
the minimum in-range signal change criteria within 2
1
/
2
minutes, the display will report a Range Fault
fault code and the ITM will return to normal operation, aborting the AutoSpan sequence. The ITM will
continue to report a Range Fault and will not clear the fault until a successful AutoSpan is completed.
5. Assuming acceptable sensor signal change, after 1 minute the reading will auto-adjust to the
programmed AutoSpan level. During the next 30 seconds, the AutoSpan sequence checks the sensor
for acceptable reading stability. If the sensor fails the stability check, the reading is re-adjusted back to
the AutoSpan level and the cycle repeats until the stability check is passed. Up to three additional 30-
second stability check periods are allowed before the display scrolls a Stability Fault fault code and
the sensor will return to normal operation, aborting the AutoSpan sequence. The sensor will continue
to report a Stability Fault and will not clear the fault until a successful AutoSpan is completed.
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.
6. Remove the span gas source and calibration adapter, or for O
2
deficiency sensors, apply N
2
at a set
flow rate of 500cc/min. The display will toggle between reporting a live reading and "REMOVE
GAS" as it clears toward "0". When the reading clears below 10% of range, the display will scroll
Span Complete and will revert to normal operation. If the sensor fails to clear to less than 10% in less
than 5 minutes, a Clearing Fault fault code will be dispalyed and the sensor will return to normal
operation, aborting the AutoSpan sequence. The sensor will continue to report a Clearing Fault and
will not clear the fault until a successful AutoSpan is completed.
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.
NOTE
Any fault during the AutoSpan will cause the current output from the sensor to drop to
3.25mA.
3.4 Fault Diagnostic/Failsafe Feature
If the ITM should incur a fault, the ITM will drop the mA output to 1.2mA (without display) or 3.25mA (with
display). This can occur if the ITM;
 detects a problem with the sensor,
 detects that there is no sensor cell connected, or
 detects an internal ITM fault.
The ITM will hold the fault current output until the problem is resolved. If the DM-100 Display is installed,
the display will show an error code. The error codes are defined in Section 5, Troubleshooting Guide.