Detcon DM-700 - Manual (Page 10)

Model DM-700
DM-700 Instruction Manual Rev. 4.0 Page 6 of 48
10. The sensor power supply common (black wire) must be referenced to the metal enclosure body
(ground) during installation.
11. These sensors meet EN60079-0:2009, EN60079-1:2007, EN60079-11:2012 and EN 50020
12. These sensors have a maximum safe location voltage of Um=250V.
13. These sensors pass dielectric strength of 500VRMS between circuit and enclosure for a minimum of 1
minute at a maximum test current of 5mA.
2.2 Sensor Placement
Selection of sensor location is critical to the overall safe performance of the product. Six 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) Maintenance access
(6) Additional placement considerations
Density
Placement of sensors relative to the density of the target gas is such that sensors for the detection of heavier
than air gasses should be located within 4 feet of grade as these heavy gasses will tend to settle in low lying
areas. For gasses lighter than air, sensor placement should be 4-8 feet above grade in open areas or in pitched
areas of enclosed spaces.
Leak Sources
The 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.
Maintenance Access
Consideration should be given to providing easy access for maintenance personnel. Consideration should also
be given to the consequences of close proximity to contaminants that may foul the sensor prematurely.
NOTE: All installations of the gas sensor should point straight down (refer to Figure 9).
Improper sensor orientation may result in false readings and permanent sensor damage.