2.5 Pneumatic Installation
Pneumatic system connections depend on whether reference air set, calibration solenoids, and/
or blowback equipment options are equipped on your transmitter. Refer to the following
paragraphs and select the option that applies to your transmitter configuration.
2.5.1 Reference Air Set Option (only)
When no options or only the reference air set option is equipped, use the following procedure to
install the pneumatic system components.
1. Refer to Figure 2-10. Connect the reference air set (regulator/filter and pressure gage) to the instrument air
inlet on the electronics housing and to the inlet side of the dilution air flow meter.
2. Connect the dilution air flow meter output to the dilution air inlet fitting on the sensor housing.
3. Install an air line between the instrument air outlet fitting on the electronics housing and the tee fitting on
the sensor housing.
Do not use 100% nitrogen as an O
2
low gas. It is suggested that O
2
low gas be between
0.4% and 2.0% O
2
. Do not use gases with hydrocarbon concentrations of more than 40
parts per million. Failure to use proper gases will result in erroneous readings.
4. One CO gas and two O
2
gases are used to calibrate the Hazardous Area OCX 8800:
• CO - 1000 ppm or up to 4%, Balance air
• O
2
low gas - 0.4% , Balance N
2
• O
2
high gas - 8%, Balance N
2
5. Connect the output of the test gas sources to the inlet port of the CAL GAS flow meter. Install an air line
between the flow meter outlet port and the CAL GAS inlet fitting on the sensor housing.
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