Detcon PI-500 - Manual (Page 15)

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 f langes, 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 eff icient 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 person-
nel 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.
Maintenance Access
Consideration should be given to easy access by maintenance personnel as well as the consequences of close proximity
to contaminants that may foul the sensor prematurely.
Note: In all installations, the sensor element in SS housing points down relative to grade (Fig. 1). Improper sensor ori-
entation may result in false reading and permanent sensor damage.
3.4.3 Local Electrical Codes
Sensor and transmitter assemblies should be installed in accordance with all local electrical codes. Use appropriate con-
duit seals. Drains & breathers are recommended. The sensor assemblies are suitable for Class I; Groups B, C, D; Div. 1
environments.
PI-500 Toxic Gas Sensors PG.15
EYS
Seal
Fitting
Drain
“T” Plug any unused ports.