What Chris said. This is just FYI!!!!!
It is from THe Cloud Ceiling Study, as a matter of interest: (it refers to max width of gap to NOT need sprks above) 4.3 Conclusions from Modeling In general there was not a large variance in permissible gap size as a function of height for a given cloud-fire configuration. The criteria that failed may have varied over the height, but the gap size at which failure occurred remained fairly constant. With the exception of the cloud-wall configuration, the plenum height also did not have a large impact on the permissible gap size. The most restrictive gap size was the cloud-corner configuration with a gap size of 8.5 %. The least restrictive was the cloud-cloud-slot configuration which did not fail for the gap sizes tested. It is noted that an 8.5 % gap for an 8 ft cloud height is an 8 in gap which is the maximum gap size recommended in the Wellen study. However, the current study indicates that one could allow that gap to be proportionately larger for higher ceiling heights. 5.2 Recommendations for Gap Sizes The result of modeling a large number of configurations of room geometry and cloud-fire configuration was that the permissible gap size is a function of ceiling height. Two potential rule sets are proffered based upon these results: a single rule applied to any cloud and a two part rule with variance for cloud-wall and cloud-cloud gaps. 5.2.1 One Part Rule For cloud ceilings where the clouds and structural ceiling are of non-combustible construction, the clouds are sufficiently large and spaced such that each cloud will have at least one sprinkler based upon the normal listed spacing, and where the clouds are level and co-planar, sprinklers can be omitted on the structural ceiling if: The gap between a wall and any cloud or between two adjacent clouds is less than or equal to 1 inch of gap per foot of ceiling height. 5.2.2 Two Part Rule For cloud ceilings where the clouds and structural ceiling are of non-combustible construction, the clouds are sufficiently large and spaced such that each cloud will have at least one sprinkler based upon the normal listed spacing, and where the clouds are level and co-planar, sprinklers can be omitted on the structural ceiling if: The gap between a wall and any cloud is less than or equal to 1 inch of gap per foot of ceiling height, or The gap between any two adjacent clouds is less than or equal to 1 ¼ inch of gap per foot of ceiling height. -----Original Message----- From: Cahill, Christopher [mailto:[email protected]] Sent: Monday, April 21, 2014 9:49 AM To: [email protected] Subject: RE: Ceiling Clouds Again I use the 12" from the ceiling then protect under obstructions over 4' wide rules. With that simple explanation I've never had an arch not get it. Of course I've never had an arch care about above the ceiling. Just why we're putting them in their clouds. Chris Cahill, PE* Associate Fire Protection Engineer Burns & McDonnell Phone: 952.656.3652 Fax: 952.229.2923 [email protected] www.burnsmcd.com *Registered in: MN Proud to be #14 on FORTUNE's 2014 List of 100 Best Companies to Work For -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Mike Hairfield Sent: Monday, April 21, 2014 9:16 AM To: AFSA SprinklerFORUM Subject: Ceiling Clouds Again I should have saved all the info on Ceiling Clouds but to no avail I deleted them. OK here is my situation, the room has a ceiling that the opening between the wall and ceiling is 24" wide. The room is approximately 24' wide by 40' long also in the middle of the room is a 24" wide gap between the ceilings. The ceiling height is 9'-0" A.F.F. and the roof deck is 14'-0" to t.o.s. The Architect can not understand that this room needs sprinkler protection above and below. Now where in NFPA-13 do I find this requirement? Thanks, Mike _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
