#023 NFPA 72: 7 Differences between FM and NFPA 72

Who are they?

FM Global:
The Factory Mutual Research Corporation is an organization financially supported by three Industrial Risk Insurance Companies. FM’s research, engineering, education, testing, and approval are aimed at the risk reduction and property protection of its policyholders through the setting and implementation of construction and operation practices.

Purpose – Client value conservation by minimizing the risk of property damage and business interruption.

The National Fire Protection Association is an independent organization whose interest is the development of codes, standards, recommended practices, and guides for the education and furthering of fire safety practices in North America and around the world. Members include individuals, corporations, trade, or professional associations, institutes, fire departments, fire brigades, and any other private or public agencies desiring to advance the purposes of the association.

Purpose – Main objective is life safety. Some property protection and minor societal impact.

Now that we know that they are different, here are other differences between them:

  1. FM : Different temperatures (Table 1.Selection of detector temperature rating).
    NFPA: Table Temperature classification and color code for heat-sensing fire detectors.
  2. FM : Location: on the ceiling not less than 0.04H from sidewall or on the sidewalls between 0.04H and 0.12H from the ceiling.
    NFPA: Location: on the ceiling not less than 4in. from sidewall or on the sidewalls between 4in. and 12in. from the ceiling.
  3. FM : Different spacing Table 2. Heat detector spacing.
    NFPA: Table A. Test spacing for spot type heat detector.
  4. FM : For beam construction, if D/H (Beam depth/Ceiling height) is greater than 0.10 and W/H (radio of the beam spacing/H) is greater than 0.30, locate detectors in each pocket. Otherwise, mount detectors on the bottoms of the beams.
    NFPA: Beam construction: if D/H is greater than 0.10 and W/H is greater than 0.40, heat detectors should be located in each beam in each pocket. Otherwise, should be installed on the bottoms of the beams.
  5. FM : For joisted and beam ceilings deeper than 3% of the ceiling height, do not exceed 50% of the detector’s smooth ceiling spacing, as measure at right angles to the joist and beams.
    NFPA: Where beams project more than 4in. below the ceiling, the spacing of spot-type heat detectors at right angles to the direction of beam travel shall be not more than 2/3 of the listed spacing.
  6. FM : Different detector spacing reductions Table 3. Heat detector spacing reductions for ceilings higher than 10 ft (3m).
    NFPA: Table Heat detector spacing reduction based on ceiling height.
  7. FM : Beam-type photoelectric detectors: install the beam detectors 30ft (9m) or less apart with one-half or less spacing to side walls.
    NFPA: Projected beam-type detector: a spacing of not more than 60ft (18.3m) between projected beams and not more than one-half that spacing between a project beam and a sidewall should be used as a guide.


Por Ing. Emma Karen Martínez Garduño

BDE Mayo 2017

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