Detcon DM-534C - Manual (Page 10)

DM-534C Oxygen Sensor Assembly
DM-534C O2 Sensor Instruction Manual Rev.1.4 Page 6 of 18
The RS485 (if applicable) requires 24 gauge, two conductor, shielded, twisted pair cable between sensor and
host PC. Use Belden part number 9841. Two sets of terminals are located on the connector board to facilitate
serial loop wiring from sensor to sensor. Wiring designators are A & B (IN) and A & B (OUT).
6.2 Sensor Location
Selection of sensor location is critical to the overall safe performance of the product. Five factors play an
important role in selection of sensor locations:
(1) Density of the gas to be detected
(2) Most probable leak sources within the industrial process
(3) Ventilation or prevailing wind conditions
(4) Personnel exposure
(5) Accessibility for routine maintenance
Density - Placement of sensors relative to the density of the target gas is such that sensors for the detection of
heavier than air gases should be located within 2-4 feet of grade as these heavy gases will tend to settle in low
lying areas. For gases lighter than air, sensor placement should be 4-8 feet above grade in open areas or in
pitched areas of enclosed spaces.
Leak Sources - Most probable leak sources within an industrial process include flanges, valves, and tubing
connections of the sealed type where seals may either fail or wear. Other leak sources are best determined by
facility engineers with experience in similar processes.
Ventilation - Normal ventilation or prevailing wind conditions can dictate efficient location of gas sensors in a
manner where the migration of gas clouds is quickly detected.
Personnel Exposure The undetected migration of gas clouds should not be allowed to approach concentrated
personnel areas such as control rooms, maintenance or warehouse buildings. A more general and applicable
thought toward selecting sensor location is combining leak source and perimeter protection in the best possible
configuration.
Note: In all installations, the sensor points down relative to grade (Figure 6). Improper
sensor orientation may result in false reading and permanent sensor damage.