8.6.5.2.1.5 obstructions spaced on opposite sides

[mcarewm]

NFPA 13 8.6.5.2.1.5 . Permits heads to be spaced on opposite sides of Obstructions so long as the obstruction is not over 4'-0" .

My question is - This only applies to obstructions not more than 18" below ceiling . So if I can not meet the requirments of Tables 8.6.5.1.2 , 8.6.5.1.2(a) & 8.6.5.1.2(b) and the obstruction is lets say 20" below , I would be required to put a head in it/under it .

I just discussed this with fellow designer in my office and we both see it differently . I think we need a head he thinks as long as we are not over spaced from the center of the obstruction we don't need a head .

cheers .

 

[TravisMack]

The spacing of heads on both sides of an obstruction falls under the "beam rule" criteria. This is when the sprinkler can't spray over the top of the obstruction. When the sprinkler deflector is above the obstruction, you need to look at the criteria for the 3x rule. Also, when you read further, you will see that in light and ordinary hazard areas, the 3x rule only applies to structural members.

That is at least how I recall it from some of the seminars I have been to.

Travis Mack
MFP Design, LLC

http://www.mfpdesign.com