2. Installation
WARNING
This detector is designed for use in Zone 1 and Zone 2 hazardous
areas, and is certified Ex db IIC T6 Gb for operation up to 70°C
(158°F). Installation must be in accordance with the recognized
standards of the appropriate authority in the country concerned.
For further information please contact Crowcon. Prior to carrying
out any installation work ensure local regulations and site
procedures are followed.
2.1 Location
The detector should be mounted where the gas to be detected is most likely to
be present. The following points should be noted when locating gas detectors:
• To detect gases which are lighter than air, detectors should be mounted at
high level and Crowcon recommend the use of a collector cone (Part No.
C01051).
• To detect heavier than air gases, detectors should be mounted at low level.
• When locating detectors consider the possible damage caused by natural
events e.g. rain or flooding. For detectors mounted outdoors Crowcon
recommend the use of a Spray Deflector (Part No. C01052).
• Consider ease of access for functional testing and servicing.
• Consider how the escaping gas may behave due to natural or forced air
currents. Mount detectors in ventilation ducts if appropriate.
• Consider the process conditions. For example, butane is normally heavier
than air, but if released from a process which is at an elevated temperature
and/or pressure, the gas may rise rather than fall.
• Location of oxygen sensors requires knowledge of the gas that may
displace the oxygen. For example, carbon dioxide is denser than air and
therefore is likely to displace oxygen from low levels upwards.
• Sensors should be mounted at head height (1.5m nominally) to detect
gases of a similar density to air, assuming that ambient conditions and the
temperature of the target gas are nominally 20˚C.
The placement of sensors should be determined following advice of experts
having specialist knowledge of gas dispersion, the plant processing equipment
as well as safety and engineering issues. The agreement reached on the
locations of sensors should be recorded.
