Most of our work in done in Delaware where the 10 PSI safety margin has been in place since before I started. I guess I take it for granted anymore, and we have what I would consider not-great water. You're not likely to get anything above 50 PSI static anywhere in the state. Maybe 60 if you're lucky. Flows are in the 1000s. But I seriously don't even notice it anymore. I try and shoot for 15-17 PSI to give our fitters some cushion for minor field variations, but sometimes you can't do that and you have to live with 11 or even 10.1. That 10 PSI isn't for field changes either, its specifically for water supply degradation and fluctuation.
Its interesting to hear about the water level being lower in the winter too, winter flow tests here are always 3-4 PSI higher and have better flow vs the summer. I have been seeing a lot of single hydrant flow tests lately which is troubling. I mean at the end of the day, 13 will get modified or overwritten by the building code adopted or some other ordinance or legislative change, so why is this any different? States and towns have been deleting adding and modifying sections of code forever, so if your local jurisdiction doesn't like the 10 PSI, just change it when its adopted. Benjamin Young On Mon, Jun 18, 2018 at 1:20 PM, Daniel Arnold <[email protected]> wrote: > But Horror stories have been the basis for ‘safety margins’ in our codes > and standards since their inception... including NFPA 13. > > There have been amazing strides made in understanding and quantifying > the dynamics of sprinkler performance, limitations, etc. over the past 30 > years and incorporating that knowledge into NFPA 13. A defined safety > factor in hydraulic calculations is but one logical step in the continuing > maturation of 13 and will eventually be in the standard. The more useful > discussion is how it should be quantified and Incorporated. I agree with > Scott and share his experiences....NFIRS stats are not helpful in > justifying technical stagnation. > > I absolutely understand and agree with the position that a safety factor > is already baked in the standard but what is it? Saying it’s “enough” > without being able to eventually define it doesn’t help further progress. > > ... 2 cents from a lurker (usually 😉) > > Daniel Arnold, PE, FSFPE > Seneca Fire Engineering, LLC > Atlanta, Georgia > > Daniel L. Arnold, PE, FSFPE > Sent from my iPhone > > On Jun 18, 2018, at 11:34 AM, Mark Sornsin [FAR] <[email protected]> > wrote: > > All of the horror stories in the world do not change the fact that > requiring a specific safety margin for calculations is difficult to justify > in an internationally recognized standard. I could see Annex language > offering pros for a margin and maybe giving examples of when one might be > considered. > > > > In my view it’s the responsibility of the person engineering the system to > make this call. In this industry 99% of the time that is the designer > working for the low-bid contractor. The designer who may or may not be > NICET certified, depending on the rules of the jurisdiction in which they > are working. The point is the person with the most knowledge of the local > conditions should be making this call. In an ideal world, when you have > someone specifying the design parameters for a bid project, it would be the > specifying engineer. I also realize that this is fantasy 98% of the time, > which is a stain on the engineering profession, but that’s a different > rant. We can’t expect to codify a requirement like this in a standard that > needs to apply throughout the world. It would require specific numbers and > these will vary on local conditions. Instead it is the engineer/designers > responsibility to become familiar with local conditions and adjust > accordingly. The example of reduced water levels in municipal water towers > is a great one. Not all cities engage in this practice, but where they do > the designer needs to know what the minimum static pressures can be. Or > the local reviewing authority needs to adopt specific requirements to match > their local conditions. > > > > But the real problem comes when a contractor is bidding on a job with no > real engineering guidance and no local amendments to account for special > local conditions. The low-bid contractor or will be the one who assumes > their water test is valid despite having taken it at the highest possible > pressure of the day/season. And a specific safety margin requirement in > NFPA 13 cannot guarantee proper correction for this error. > > > > <image1fad98.JPG> <http://www.SummitCoUS.com> Mark Sornsin > Sr. Fire Protection Engineer > Direct: 701-499-1391 > Cell: 701-526-8585 > > *From:* Sprinklerforum [mailto:[email protected]. > org <[email protected]>] *On Behalf Of *Scott > Futrell > *Sent:* Saturday, June 16, 2018 9:51 AM > *To:* [email protected] > *Subject:* RE: Safety Margin > > > > As a plan specifier, plan reviewer and an investigator I see designs right > to the supply and then as-built conditions far worse (read more demanding) > than the design submitted with the calcs. This is not a regional > observation. > > > > Additionally, I am aware of communities that lower elevated tank levels > 20’ in winter to lower heating costs. Contractors in those areas do NOT > adjust flow tests for this seasonal variation. > > > > No safety margin what-so-ever in NFPA 13 is unreasonable for a design > standard. > > > > Arguments on the floor including ‘requiring all systems to have back-up > power’ were ridiculous. > > > > Scott > > > > Office: (763) 425-1001 x2 > > Cell: (612) 759-5556 > > > > *From:* Sprinklerforum [mailto:[email protected]. > org <[email protected]>] *On Behalf Of *Steve > Leyton > *Sent:* Friday, June 15, 2018 2:16 PM > *To:* [email protected] > *Subject:* RE: Safety Margin > > > > That was the conversation on the floor of the code hearing. The concerns > underscored by the CAM were not about whether safety factor is a good > practice, it was that a fixed minimum value as high as 10 PSI could trigger > all sorts of cost-impact consequences, particularly in areas where > pressures are middling to poor – in Rhode Island, 10 PSI could be 25-30% of > the available pressure. > > > > In the West, due primarily to the politics of drought, water districts are > using models in lieu of physical flow tests. Prudent and conservative > programming makes it possible for them to issue safeguarded values from > which it’s not necessary to reduce the available pressure. For ex., City > of San Diego uses a three-level safety factor in their (highly accurate) > models: starting with legacy drought water levels in the reservoirs, then > factor the highest seasonal demand, then the highest peak day demand of > that season. The values we’re getting are usually significantly lower > than what can be measured on the hydrant, and this practice isn’t without > controversy because there are obvious complications that can and do occur, > particularly with existing systems based on 20-year old (and older) > pressures that were physically measured (with crappy equipment) when first > designed and built. > > > > But if modeling becomes the new normal, prudent water district engineering > departments and fire departments they serve can coordinate manipulating > data to include reasonable safety factors. The range of variation in > pressures, accuracy of flow test equipment, the use of modeling in many > areas … there are too many variables to set a fixed minimum safety factor > based on PSI, IMHO. > > > > SML > > > > *From:* Sprinklerforum [mailto:[email protected]. > org <[email protected]>] *On Behalf Of *Parsley > Consulting > *Sent:* Friday, June 15, 2018 12:00 PM > *To:* [email protected] > *Subject:* Re: Safety Margin > > > > Richard, > > If my memory is accurate of the issues raised in the discussion that > ambiguity was a part of the differing viewpoints. > > Some argued that 10 psi was not workable in their locale as their > pressures were so limited that an imposition of 10 psi was simply to > drastic and would result in much larger pipe sizes as a result. > > Others argued that 10 psi was not enough, and in their area 10 psi didn't > equal 10%, and there was some reluctance to base their designs on a > pressure greater than 90% of the available. > > It was quite a discussion. > > > *Ken Wagoner, SET * > > > *Parsley Consulting 350 West 9th Avenue, Suite 206 Escondido, California > 92025 * > *Phone 760-745-6181 Visit the website <http://www.parsleyconsulting.com/> * > > On 06/15/2018 10:23 AM, Richard Carr wrote: > > Even though it is not in NFPA most AHJ’s require some sort of safety > margin, 10%, 10 psi which we have had to provide for a long time so most > designers know to leave safety margin in the calc’s. it would be nice if > they all used the same amount. > > > > Richard M. Carr, SET > > Project Manager/Design > > Diboco Fire Sprinklers, Inc. > > 325 Jackson Loop Road > > Flat Rock, NC 28731 > > > > [email protected] > > 828-696-3400 > > 828-696-2288 Fax > > 828-708-9118 Mobile > > > > <image001.jpg> > > > > <image002.png> > > > > > > *From:* Sprinklerforum <[email protected]> > <[email protected]> *On Behalf Of *Parsley > Consulting > *Sent:* Friday, June 15, 2018 1:22 PM > *To:* [email protected] > *Subject:* Safety Margin > > > > Scott, > > Based on the material which was presented to the -24 and -291 committee > meetings I believed the proposed safety margin and the means to calculate > that margin there was some merit in the proposal. > > For reasons I don't quite remember the PI was voted down at the 2nd draft > meeting. I listened to some of the discussion, and there were some good > points made. I'm not terribly surprised it failed at the convention > level. Perhaps the attendees were following the lead of the technical > committees, and declining to overrule their decision. > > sincerely, > > > *Ken Wagoner, SET **Parsley Consulting* > > > * 350 West 9th Avenue, Suite 206 Escondido, California 92025 * > *Phone 760-745-6181 Visit the website <http://www.parsleyconsulting.com/> * > > On 06/15/2018 8:09 AM, Scott Futrell wrote: > > Only that the 'safety margin' inclusion in the 2019 edition of NFPA 13 > failed, so it won't be included or required. > > > > I consider this unfortunate, but I'd guess that not everyone on the forum > would agree. > > > > Scott > > > > Office: (763) 425-1001 x2 > > Cell: (612) 759-5556 > > > > -----Original Message----- > > From: Sprinklerforum [mailto:[email protected] > <[email protected]>] On Behalf Of > [email protected] > > Sent: Thursday, June 14, 2018 5:46 PM > > To: [email protected] > > Subject: NFPA Vegas Convention > > > > I didn't make it again this year. > > "Caputo" is the only speaker name I recognized. > > Anybody have any earthshaking epiphanies? > > > > > > _______________________________________________ > > Sprinklerforum mailing list > > [email protected] > > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org > > _______________________________________________ > > Sprinklerforum mailing list > > [email protected] > > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org > > > > > > > > _______________________________________________ > > Sprinklerforum mailing list > > [email protected] > > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org > > > > > ______________________________________________________________________ > This email has been scanned by the Symantec Email Security.cloud service. > For more information please visit http://www.symanteccloud.com > ______________________________________________________________________ > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler. > org > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler. > org > >
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