Emerson Rosemount 936 Reference Manual page 32

Installation
October 2021
5.2.3 Site requirements
When installing the Rosemount 936, take into account the weight of the monitored gas
compared to that of the surrounding air and the individual site requirements.
Ensure that the site selected gives the detector a direct view to the source. The mounting
point for each item should be secure and stable with minimal vibrations. Mount the
equipment in a position where it cannot be knocked out of alignment and is guarded from
physical impact.
5.2.4 Source and detector
Select the appropriate detector for the length of open path to be monitored.
To allow for aging of the source and a reduction of the ultraviolet (UV) signal due to
adverse weather, Emerson recommends using a detector that is not at the limit of its
operating range.
The general recommendation is to install the detector at a distance from the source of not
more than 75 percent of the specified operating distance. In severe weather conditions,
such as offshore oil production and exploration, reduce this distance to 50 percent.
Keep the path between the source and detector clear of any obstacles that might hinder
the free movement of air in the protected area or block the UV beam.
5.2.5 Tips for gas detector locations
To provide the best detection coverage, install the detector:
• Below potential leak source for gases heavier than air.
• Above potential leak sources for gases lighter than air.
• Near to leak sources along the expected leak trajectory, taking into account prevailing
wind directions.
CAUTION
For optimal performance, avoid placing the detector in locations frequently covered by
steam.
5.2.6 Separation distances
To avoid cross talk between adjacent Open Path Gas Detector (OPGD) systems where
transmitters are installed on the same side, keep the relevant separation distance between
the neighboring OPGD systems according to the installation lengths as listed in
Table 5-2: Minimum Separation Distances
Installation line of sight distance, ft. (m)
33 (10)
66 (20)
32
Minimum separation, ft. (m)
3.3 (1)
5 (1.5)
Emerson.com/Rosemount
Reference Manual
00809-0100-4036
Table 5-2.