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.126.96.36.199 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.188.8.131.52.)
Hope this answers to your satisfaction.
Detector installation must comply with local regulations. UL listed products must comply with NFPA72 Ensure clear line of sight between Detector and Reflector – it is recommended at least 0.5m radius of clear space be maintained around the centre of the beam path Mount securely to solid structural surfaces Position beam as high as possible, but with a minimum distance of 0.5m from Detector to ceiling. For installations complying with UL268/NFPA72, the maximum distance of Detector and Reflector from the ceiling must be 10% of the distance between floor and ceiling Mount Detector and Reflector directly opposite each other Do NOT position Detector where personnel or objects can enter beam path Do NOT position two Detectors facing each other Do NOT install the Detector or Reflector in environments where condensation or icing are likely to occur For ranges between 5m and 50m, use a 50m Detector with 1 Reflector. For ranges between 50m and 100m, use a 100m Detector with 4 Reflectors
Position beam as high as possible, but with a minimum distance of 0.5m from Detector to ceiling
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