I am installing Beam detector in atrium area (Width 3Mtr, Length 74Mtr, Height 9Mtr). Please advise me about ceiling to Beam detector height, that I can keep for installation .
You can actually install them on different heights, if you want more levels of detection.
Plus if this also controls a smoke removal system, need to coordinate with all other systems.
I found the reference in Annex A of NFPA 72.
Quoting: A.18.104.22.168 On smooth ceilings, a spacing of not more than 60 ft (18.3 m) between projected beams and not more than
one-half that spacing between a projected beam and a sidewall (wall parallel to the beam travel) should be used as a guide. Other spacing should be determined based on ceiling height, airflow characteristics, and response requirements. In some cases, the light beam projector is mounted on one end wall, with the light beam receiver mounted on the opposite wall. However, it is also permitted to suspend the
projector and receiver from the ceiling at a distance from the end walls not exceeding one-quarter the selected spacing
(S). (See Figure A.22.214.171.124.)
Hope this answers to your satisfaction.
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