I think the hazard is the most important part of the equation. If it is light or ordinary hazard I don't think is much matters. The heads located at the deck will activate first cooling those below the pipe rack.
If it's a hazardous manufacturing building the obstructions need to be evaluated. If it is ESFR then absolutely it's an obstruction. FM has some information on water shields for heads under round ducts in ESFR systems that could be applied to pipe racks if so inclined. Ron Fletcher Aero Automatic Phoenix, AZ -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Todd Williams - FPDC Sent: Wednesday, July 09, 2008 8:07 AM To: [email protected] Subject: Re: Treatment of pipe racks as obstructions Jim, Another area with many shades of gray...... I have run in to this at several hospitals and manufacturing facilities. Whether it will act as an obstruction is somewhat a function of how closely they space the pipe/conduit/cable trays. There is no clear definition of good or bad. Colloquially, if you can't see the sprinkler through the pipe rack (or have to squint to find it), then it is an obstruction. If you can see it, then it becomes judgement if it does obstruct the discharge. Lately I have found that if the facility has an HPR carrier, they tend to require sprinklers below most all of these racks. As far as "collection", I don't think that is a path we want to go down. I do tend to treat these similar to a grated floor and recommend sprinklers with water shields, similar to rack sprinklers. It would be really nice if someone could come up with a consensus of when two objects are sufficiently close that they act as one. At 10:23 AM 7/9/2008, you wrote: >All, > >Maybe I am not looking in the right sections, but I have not found 13, 8.5 >and 8.6 to be particularly useful in addressing pipes on pipe racks. > >For example, you have a situation where a pipe rack 5 ft. below sprinklers >that is 6 ft. wide with pipe diameters up to 8" (including insulation" >with varying spaces between pipes. What is the consensus on pipe size >and spacing of pipes in a rack before it is considered a true obstruction? > I realize the conservative approach would be to provide sprinklers under >the pipe rack, but that is not always feasible. This seems to be a gray >area. What about 2 tier pipe racks? > >If sprinklers are installed beneath racks, what is the consensus on heat >collection methods. There are differing opinions and studies on this. >Some say 12" x 12" collectors with downturned edges are good or not good. >Some say flat 12" squares are better. Others say no to both or state that >collectors need to be much larger. > >Similar questions relating to cable trays. > >What say you guys and gals? > >Thanks, > >James L.(Jim) Roberts, PE/SET >Fluor Corporation >100 Fluor Daniel Drive - C104F >Greenville, SC 29607 >864.281.5149 >864.281.4916(Fax) >------------------------------------------------------------ >The information transmitted is intended only for the person >or entity to which it is addressed and may contain >proprietary, business-confidential and/or privileged material. >If you are not the intended recipient of this message you are >hereby notified that any use, review, retransmission, dissemination, >distribution, reproduction or any action taken in reliance upon >this message is prohibited. If you received this in error, please >contact the sender and delete the material from any computer. > >Any views expressed in this message are those of the individual >sender and may not necessarily reflect the views of the company. >------------------------------------------------------------ >_______________________________________________ >Sprinklerforum mailing list >[email protected] >http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > >To Unsubscribe, send an email to:[EMAIL PROTECTED] >(Put the word unsubscribe in the subject field) Todd G. Williams, PE Fire Protection Design/Consulting Stonington, Connecticut www.fpdc.com 860.535.2080 _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
