NFPA 13 Mech room duct obstruction

[ContractorDave]

Duct work off of an air handling unit is 8' wide (x 4' high) and runs the entire length of one side of a mechanical room at 16" off the floor. What section addresses this? Does the section indicate a 'height off the floor' minimum?
Thanks

 

[LCREP]

See NFPA 13, 02 8.5.5.3, and 8.5.5.3.1, no exception for height, provide sprinkler protection under the duct.

 

[LCREP]

Is it 16 inches or 16 feet?? If 16 inches and NO storage below, what will burn?? If 16 feet then see my comments above.

 

[cdafd]

Plus if it is 16 inches, you have to fit the pipe in there and you can have the head up to one foot down, so you might be protecting four inches underneath

 

[ContractorDave]

Thank you for your posts. It is 16 inches. In this case there is minor storage, but at issue is; in a sprinklered room where duct work is an obstruction under 8.5.5.3, is there a height off the floor where the rule does not apply? IE 6"? Is storage under the duct of consequence, for as noted, at 16' sprinklers would be required, storage or not.

 

[cdafd]

would not require it if it is not going to do any good, but have required heads under low duct work.

You have to get the head piped there and be able to get the head put on and take it off. also the four inch minimum 8.8.3.3 2002 edition not sure if it applies.

 

[SprinklerDesigner2]

NFPA #13 doesn't address every issue and I find it hard to believe the standards intent was to require sprinklers in that space.

It's never been the standards intent to require all areas of the floor be wetted either.

This place can't be used for storage so what is there to burn?