Detcon IR-700 - Manual (Page 15)

Model IR-700
IR-700 Instruction Manual Rev. 3.1 Page 11 of 40
The RS-485 (if applicable) requires 24 gauge, two conductor, shielded, twisted pair cable between sensor and
host controller. General Cable Commodore part number ZO16P0022189 is recommended.
NOTE: Install a 120 ohm resistor across A & B terminals on the last sensor in the serial loop.
d) Trim all exposed wire leads if they are not permanently landed in a terminal block.
e) Replace the junction box cover.
2.7 Initial Start Up
Upon completion of all mechanical mounting and termination of all field wiring, apply system power in the
range of 11.5-30 VDC (24 VDC typical) and observe the following normal conditions:
a) IR-700 display reads “0”, and no fault messages are flashing.
b) A temporary non-zero reading may occur as the sensor reaches stabilization. The reading will converge to
“0” within 1-2 minutes of power-up, assuming there is no combustible gas in the area of the sensor.
NOTE: The 4-20mA signal is held constant at 4mA for the first two minutes after power up.
Initial Operational Tests
After a warm up period of 1 hour, the sensor should be checked to verify sensitivity to combustible gas. For
the IR-700 CO
2
series sensors, test the sensor with a suitable CO
2
span gas.
Material Requirements
 Detcon PN 613-120000-700 700 Series Splash Guard with integral Cal Port –OR-
 Detcon PN 943-000006-132 Threaded Calibration Adapter
 Detcon PN 942-520124-050 Span Gas; 50% LEL methane/balance Air at fixed flow rate of 200
cc/min (for 0-100% range)
 Detcon PN 942-520124-025 Span Gas; 25% LEL methane/balance Air at fixed flow rate of 200
cc/min (for 0-50% range)
a) Attach the calibration adapter to the threaded sensor housing. Apply the test gas at a controlled flow rate
of 200cc/min. Allow 1-2 minutes for the reading to stabilize. Observe that during the 1-2 minutes the
ITM display increases to a level near that of the applied calibration gas value.
b) Remove test gas and observe that the ITM display decreases to “0”.
Initial operational tests are complete. Detcon IR-700 combustible gas sensors are factory calibrated prior to
shipment, and should not require significant adjustment on start up. However, it is recommended that a
complete calibration test and adjustment be performed 16 to 24 hours after power-up. Refer to zero and span
calibration instructions in Section 3.4.