Detcon CXT-DM User Manual download pdf (Page 12)

Model CXT-DM

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) Placement of transmitting antenna

(6) Maintenance access

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 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

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: In all installations the gas sensor should point straight down (refer to Figure 11).

Improper sensor orientation may result in false readings and permanent sensor damage.

Placement of RF Antenna

Placement of the sensor should also have consideration made for line of sight RF Transmissions. The devices

should be placed in a reasonable proximity to other devices in the network. Obstacles between CXT

transceivers can impact RF line-of-sight and may result in communication problems. The CXT sensor should

be in view of at least one other transceiver.

Additional Placement Considerations

The sensor should not be positioned where it may be sprayed or coated with surface contaminating substances.

Painting sensor assemblies is prohibited.

CXT-DM Instruction Manual Rev. 1.6 Page 8 of 52

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Detcon CXT-DM User Manual Page 12