Unless you're doing 13d, how often are you flowing 10 GPM to a head when a 1/2" K5.6 head flows 15 GPM at the min EHP of 7?
I can sum it up by quoting what Ken reminds me- It's not what you know, it's what you can prove. As others said, we know what it'll probably be- But without a calc per #13 (or applicable standard) how can you prove it? Here's a real-life example I've used before, illustrating what we thought were the needed steps as this unfolded: Got a plan of a former staples store being converted to a fitness center. Our scope is to add about 25 heads where they'll add locker rooms and office. Light hazard in former oh2 occupancy, we figure no calc necessary- We'll do a quick flow test (or see if one's on file) and confirm the supply still resembles what the job was originally calc'd to, by looking at the hydr placard. Our 1" drops to the new light hazard rooms would simply be snaps into ex branch lines. Except there's no placard. How to we prove the work we're doing meets applicable code and required density? We can't without doing what we felt we had to de as our due diligence, survey the existing grid (so we knew it wasn't an older scheduled systems from 60's or 70's) and confirm the demand for it is less than what we obtained when running the flow test. Without that calc, what would we submit? Our assumption that the job was originally installed properly, that the water supply was still adequate, so our work was then ok, too? A lot of my decision making is risk management. IF there were a fire, and we ended up in court, our defense would have been "It looked ok to us". Their atty would ask if there was a way to verify if the system wer correct and therefore our work correct that maybe we shoudn't have skipped? Our response isn't going to be "well, there were other bidders and we wanted to be low so we just figured everything was ok". Cause the next question would be "doesn't the code (the LAW) require you to provide submittals of your calculations that you seemed to have skipped?" Well, duh, yes it does- we just don't. Isn't that ok?" Their atty:"do you realize that if you'd done what the law requires you to do, Mr Washington would still be alive today?" Ok, I didn't get paid to do the survey or sketch the grid in and calc it. But there wasn't, to us, a choice to NOT do it because it is required by law and without the placard, we couldn't verify. Testing, tho, was per 13 at static since we couldn't isolate the new drops from the existing. glc -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Travis Mack, SET Sent: Wednesday, February 10, 2010 4:36 PM To: [email protected] Subject: Re: pipe sizing question Karen: That just comes from time on the 'board' doing calcs over the years. Most of us that have been doing this for more than half of their lifetime can look at a building and get a general layout and rough idea of pipe sizes by knowing available pressures. The calcs are just to confirm your best estimate. On 2/10/2010 2:23 PM, Karen Purvis wrote: > I'm not talking about calculations just about selecting the actual size of > the pipe. Should I use a 1" pipe on 2 sprinklers or use a 1" pipe as long as > the gpms are less than 10. I just want to know how people know or choose the > size of pipe they use for each branch, sprig and main. > > Karen Purvis > Senior Designer > Facility Systems Consultants > 713 South Central Street, > Suite 101 > Knoxville, TN 37902 > ph.865-246-0164 > fax 865-246-1084 > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Matt Grise > Sent: Wednesday, February 10, 2010 4:23 PM > To: '[email protected]' > Subject: RE: pipe sizing question > > In some of the jurisdictions around here the AHJ's do allow submittals > without calcs for small add/relocate, and tenant improvement work as long as > it does not exceed the original hydraulic design of the shell system > (adjusting an OH2 retail system to accommodate a LH office, etc). > > I am familiar with the pipe drop charts you are talking about. The main > issue I see with those is that it could be difficult to account for > over-flow at each head, so you could end up with more water flowing than you > anticipate. > > Matt Grisé PE*, LEED AP > Sales Engineer > Alliance Fire Protection > *Licensed in KS& MO > > 913.888.0647 ph > 913.888.0618 f > 913.927.0222 cell > www. AFPsprink.com > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Travis Mack, > SET > Sent: Wednesday, February 10, 2010 3:18 PM > To: [email protected] > Subject: Re: pipe sizing question > > It is my understanding that you need to provide calculations per NFPA > 13, or use the pipe schedule method where it is allowed. You can > estimate with tables showing pressure drops, but that likely won't > suffice for submittal to the local authorities in any where that I have > done work. > > On 2/10/2010 2:08 PM, Karen Purvis wrote: > >> We mainly do new and add-on systems a few retrofits no grids no high piled >> storage no extra hazard. Usually all light and ordinary hazard. >> >> Karen Purvis >> Senior Designer >> Facility Systems Consultants >> 713 South Central Street, >> Suite 101 >> Knoxville, TN 37902 >> ph.865-246-0164 >> fax 865-246-1084 >> -----Original Message----- >> From: [email protected] >> [mailto:[email protected]] On Behalf Of >> [email protected] >> Sent: Wednesday, February 10, 2010 4:12 PM >> To: [email protected] >> Subject: RE: pipe sizing question >> >> For what kind of systems, new, retrofits, tree, grid, etc.....? >> >> >> Craig L. Prahl, CET >> Fire Protection Specialist >> Mechanical Department >> CH2MHILL >> Lockwood Greene >> 1500 International Drive >> PO Box 491, Spartanburg, SC 29304-0491 >> Direct - 864.599.4102 >> Fax - 864.599.8439 >> [email protected] >> http://www.ch2m.com >> >> >> -----Original Message----- >> From: [email protected] >> [mailto:[email protected]] On Behalf Of Karen >> > Purvis > >> Sent: Wednesday, February 10, 2010 3:57 PM >> To: [email protected] >> Subject: pipe sizing question >> >> This may seem like a very newbie question but here goes. How do most of >> > you > >> guys size your pipe other than using a hydraulic calculation program? I >> > have > >> been using a pressure drop chart that list pressure drop and velocity in >> schedule 40 pipe for water at 60°F per 100 feet drop. So far this has >> > worked > >> for me but now I have someone questioning my method. Should I be going >> > back > >> to the pipe schedule method? >> >> >> >> Karen Purvis >> >> Senior Designer >> >> Facility Systems Consultants >> >> 713 South Central Street, >> >> Suite 101 >> >> Knoxville, TN 37902 >> >> ph.865-246-0164 >> >> fax 865-246-1084 >> >> _______________________________________________ >> Sprinklerforum mailing list >> [email protected] >> http://fireball.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 >> [email protected] >> http://fireball.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 >> [email protected] >> http://fireball.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) >> >> > > -- Please feel free to call if you have any questions or comments. Sincerely, Travis Mack, SET MFP Design, LLC 2508 E Lodgepole Drive Gilbert, AZ 85298 Office (480) 505-9271 Fax (866) 430-6107 _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.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 [email protected] http://fireball.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)
