Travis, You may be opening a can of worms trying to use dry pendents in this area. What is your ceiling density? Section 12.1.13 (NFPA 13 2002) has specific K factor requirements for different densities in storage occupancies. With dry pendents, the K factor decreases with length of the head. I pulled up the Tyco DS-2 K11.2 dry pendent sprinkler as an example. If you have 12" of insulation and are required to be 18" above that, you are looking at a 30" dry pendent. The actual K factor for a 30" dry pendent is 10.6. That would not meet the letter of the requirement of 12.1.13.3. I actuality, you would probably be meeting the intent, but could create an issue depending on who is reviewing it. It would probably make more sense to change the requirement in NFPA 13 from K factor to orifice size, because that is in reality what the makes the difference.
Todd At 01:57 PM 5/4/2009, you wrote: >There is room in the freezer, but we also have to protect the concealed >space above the freezer. Still pricing to see which is less expensive, one >system with dry pendents and detection in the concealed space, or 1 >preaction system in the cooler with SSUs and 1 wet system in the concealed >spaces. > >The benefits to the single interlock are that the capacity issues go away. >We may need 2 or more preaction systems to protect the area with double >interlock. 25' of storage and moderate water supply. Pipe is going to get >big in a hurry, therefore, capacities get big in a hurry. > >-----Original Message----- >From: [email protected] >[mailto:[email protected]] On Behalf Of Roland >Huggins >Sent: Monday, May 04, 2009 10:50 AM >To: [email protected] >Subject: Re: Preaction: single vs double > >Is there no room within the freezer considering there is a 10yr inspection >cycle on dry pendent sprinklers and a slightly higher cost? > >The 30% increase on ALL preaction systems for storage (not occupancy hazard >approach) has gone through a dance to get to ALL doing it. In the 2002 ed, >you had the option of not applying a 30% increase if you could PROVE the >water would discharge as quickly as a wet pipe system (under the old adage >that the detection went off first so not an issue). That casual philosophy >is fine for a less demanding scenario but storage can rock and roll so in >2007 it was acknowledged that we didn't really have a lot of confidence in >proving the comparison and simply required ALL to have the increase. > >Roland > >On May 4, 2009, at 10:17 AM, Travis Mack, SET wrote: > > > We have a cold storage warehouse where the owner wants a preaction > > system. > > The piping will run in a heated, combustible concealed space above the > > cooler/freezer. The cooler will be supplied with dry pendent > > sprinklers. > > There is going to be a capacity issue with this system if it is double > > interlock. If we go with single interlock, doesn't the capacity issue > > go away? Because this is storage, I believe we will still need to > > have the 30% increase in design area, correct?? Also, can I grid a > > single interlock preaction system protecting a storage occupancy? > > > > Thanks in advance for your help. > > > > Travis > > _______________________________________________ > > Sprinklerforum mailing list > > http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum > > For Technical Assistance, send an email to: > > [email protected] > > > > To Unsubscribe, send an email > > to:[email protected] > > (Put the word unsubscribe in the subject field) > > > >_______________________________________________ >Sprinklerforum mailing list >http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >For Technical Assistance, send an email to: [email protected] > >To Unsubscribe, send an email to:[email protected] >(Put the word unsubscribe in the subject field) > >__________ NOD32 4052 (20090504) Information __________ > >This message was checked by NOD32 antivirus system. >http://www.eset.com > > >_______________________________________________ >Sprinklerforum mailing list >http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum >For Technical Assistance, send an email to: [email protected] > >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 http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
