Detcon PI-700 0-500ppb - Manual (Page 19)

Model PI-700 0-500ppb
PI-700 0-500ppb Instruction Manual Rev. 0.0 Page 15 of 53
b) Verify that the AutoSpan Level is equal to the Calibration Span Gas Concentration. (Refer to View
Sensor Status in Section 3.5.1.) If the AutoSpan Level is not equal to the Calibration span gas
concentration, adjust the AutoSpan Level as instructed in Section 3.5.2 Set AutoSpan Level.
c) From Normal Operation, enter Calibration Mode by holding the programming magnet over PGM1 for 3
seconds. Note, the “V” prompt will show that the magnetic switch is activated during the 3 second hold
period. The display will then scroll “PGM1=AutoZero. . . PGM2=AutoSpan”. Hold the programming
magnet over PGM2 for 3 seconds to execute AutoSpan (or allow to timeout in 5 seconds if AutoSpan is
not intended). The ITM will then scroll “Apply XX ppm Gas”.
NOTE: Upon entering Calibration Mode, the 4-20mA signal drops to 2mA and is held at this
level until the program returns to normal operation. Modbus™ Status Register bit 14 is also set
to signify when the sensor is in-calibration mode.
d) Apply the span calibration test gas for VOC gas sensors. Open the Flow Regulator on the Cal Gas
Cylinder to deliver 1000cc/min, then adjust the Rotameter flow rate to 500cc/min. As the sensor signal
begins to increase the display will switch to flashing “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 2½ minutes, the display will report “Range Fault” twice 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.
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 unit reports a “Stability Fault” twice and the ITM will return to normal operation, aborting
the AutoSpan sequence. The ITM will continue to report a “Stability Fault” and will not clear the fault until a
successful AutoSpan is completed.
If the sensor passes the stability check, the ITM reports a series of messages:
“Span OK”
“Sensor Life XXX%”
“Remove Span Gas”
e) Remove the span gas source tubing from the Sample Port. The ITM will report a live reading as it clears
toward “0”. When the reading clears below 10% of range, the ITM will display “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” will be reported twice and the ITM will return to normal operation, aborting the
AutoSpan sequence. The ITM will continue to report a “Clearing Fault” and will not clear the fault until
a successful AutoSpan is completed.
NOTE: When calibrating sensors where there are high levels of VOC gases in the ambient
background, use Zero Air or N
2
to assist clearing to <10% of range.
f) The AutoSpan calibration is complete.
NOTE 1: Upon entering the calibration menu, the 4-20mA signal drops to 2mA and is held at
this level until the program returns to normal operation.
NOTE 2: If the sensor fails the minimum signal change criteria, a “Range Fault” will be
declared and a “Fault Detected” message will be displayed alternately with the sensor’s
current reading. The 4-20mA output will be taken to 0mA and the ‘Range Fault’ fault bit will