Sprinkler Placement Beneath Obstructions
“We have an ESFR sprinkler system installed in a warehouse where the light fixtures are over 24 in. in width. The Authority Having Jurisdiction (AHJ) is requiring an ESFR sprinkler underneath each light fixture. The question is pertaining to NFPA 13, 2016 Edition section 8.5.5.3.1.1 and whether this section is stating that the ESFR sprinkler can be installed a maximum of 3 in. from the outside of the light fixture edge, as the attached detail #1 shows. The AHJ is interpreting this section as being a maximum of 3 in. inside the light fixture from the outside edge.” We have reviewed NFPA 13, 2016 Edition that you indicated as the applicable standard. Our informal interpretation is the 3 inch restriction is beyond the edge of the obstruction. If you can’t meet the beam rule, then sprinklers are required beneath obstructions more than 2-ft wide. Technically, section 8.5.5.3.1.1 is for spray sprinklers as indicated by the 4-ft restriction. This is new criteria for 2016 edition and the same intent readily applies to ESFR (at smaller dimensions). It states: “8.5.5.3.1.1 Sprinklers shall be located below the obstruction and not more than 3 inch (75 mm) from the outside edge of the obstruction.” The text is awkward, but if interpreted to mean it must always be directly underneath the obstruction, then it must be located between the edge and no more than 3 inches in from the edge. That means it can’t be in the middle, but must be within a narrow 3-in. zone along the edge. The intent is to be below the obstruction measured vertically and no more than 3 inches outside the obstruction measured horizontally. This is confirmed by the next section that reads: “8.5.5.3.1.2 Where sprinklers are located adjacent to the obstruction, they shall be of the intermediate level rack type.” Adjacent means next to but beyond the obstruction. This section tells us that we have to be concerned about ceiling sprinklers wetting (cold soldering) the sprinklers protecting beneath the obstruction. This only occurs when the sprinkler is not covered by the obstruction. As already stated, this criteria is really for spray sprinklers. We have no intermediate ESFR sprinklers. This leaves no choice but to apply more spray sprinkler criteria from: “8.5.5.3.4* Sprinklers installed under open gratings shall be of the intermediate level/rack storage type or otherwise shielded from the discharge of overhead sprinklers.” The annex, that provides guidance to address cold soldering by making a shield, states: “A.8.5.5.3.4 Sprinklers under open gratings should be provided with shields. Shields over automatic sprinklers should not be less, in least dimension, than four times the distance between the shield and fusible element, except special sprinklers incorporating a built-in shield need not comply with this recommendation if listed for the application.” All in all, this section does help in identifying how sprinklers are supposed to be located beneath obstructions. Unfortunately, there are no English majors on the technical committee. ------------ Technical Update is prepared by the Technical Services Dept. of the AFSA: Roland Huggins, a PE registered in fire protection engineering, Vice President of Engineering and Technical Services; and Tom Wellen, a PE registered in fire protection engineering. This is provided with the understanding that the AFSA assumes no liability for this opinion or actions taken on it and they are not to be considered the official position of the NFPA or its technical committees. Copyright 2016, American Fire Sprinkler Association. All Rights Reserved. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.firesprinkler.org/private.cgi/sprinklernotes-firesprinkler.org/attachments/20161219/05afb348/attachment.htm>
