Steve, I wasn't clear, sorry. I was referring specifically and only to the residual pressure reading during a drain test. I could see how that could be confusing. Yes, the static pressure would be a definite red flag if its lower than the residual.
You mentioned commissioning in your original post, so I assumed you were dealing with a new installation as well, not an existing one that would fall under 25. When I originally wrote this last week I was coming from that frame of reference (a new installation that's getting acceptance tested). I think that explains the confusion, sorry about that. -Ben Benjamin Young On Mon, Jul 11, 2016 at 11:14 AM, Steve Leyton <[email protected]> wrote: > I’m not sure what’s to disagree with. If you see a static pressure on > the gauge (it could be during a visual and not just a main drain test) > that’s near or lower than the BOR residual demand on the calc’ card, then > you potentially have a problem. This is just comparative metrics: the > question was (if I’m recalling and paraphrasing correctly), where do we > (composite Forum) locate the BOR node for purposes of recording the > information on the calc’ card? And I said at the riser gauge for the > reasons I’ve mentioned. I’m haven’t recommended any measure of “testing” > or any other steps beyond what’s already prescribed in NFPA 25. > > > > In our little incident, the owner bit the bullet and paid for it because > the fire department stepped up and acknowledged that they had furnished the > information based on the address side and not the connection side of the > building. If they hadn’t … who knows? > > > SL > > > > > > > > *From:* Sprinklerforum [mailto: > [email protected]] *On Behalf Of *Ben Young > *Sent:* Monday, July 11, 2016 5:30 AM > > *To:* [email protected] > *Subject:* Re: Base of riser on placards > > > > Steve, > > I have to respectfully disagree with you on this. My main concern would > be the fact that the drain and gauge are so close together. On a riser > manifold, the gauge is usually directly across or slightly above the drain > location. That would be equivalent to taking the residual pressure from a > flowing hydrant, wouldn't it? > > In addition, as my original post alluded to, if your BOR node is on the > suction side of the backflow preventer, the lower flow from the drain or > inspectors test will create a higher friction loss from the backflow than > was accounted for during the hydraulic calculations (normally, I'm sure not > all BFPs have that larger pressure loss at lower flows, but most I've seen > do,). > > Just out of curiosity as well, how long was the installing sprinkler > contractor blamed for that issue you had? > > I guess my point is, we already have acceptance testing in NFPA 13, as > well as hydraulic calculation procedures, licensing (in most states) etc. > > Using the main drain test for anything other than an NFPA 25 inspection > point is slippery slope that I don't think we should be going down. > > Thanks, > > Ben > > > > Benjamin Young > > > > On Fri, Jul 8, 2016 at 1:43 PM, Steve Leyton <[email protected]> > wrote: > > I’ve always looked at it as a red-flag benchmark. The residual demand at > BOR takes static lift and friction loss to the remote area into account, so > if I do a main drain test and I look at the calc’ card and read that the > demand is … whatever, 63.5 PSI @ 331.7 GPM. And then I look at the gauge > and it says 89 PSI static. And then I open the main drain and residual > drops to 81 PSI … great. But if I open that drain and it drops to 60 PSI > or if look at static and it says 68 PSI and then drops to 60 … then > something is amiss. I have actually seen commissioning testing where the > main drain flow test on final inspection called attention to the fact that > the flow test was taken on a different main than the one feeding the > system. And it turned out that the one feeding the system was separated > from the rest of the public system zone by a pressure regulating station. > And that the entire system was not hydraulically capable of meeting its > demand. > > > > Extreme example to be sure but if you have even a passing understanding of > hydraulics, comparing the main drain test results to the BOR demand is a > substantive metric. > > > > SL > > > > *From:* Sprinklerforum [mailto: > [email protected]] *On Behalf Of *rongreenman > . > *Sent:* Friday, July 08, 2016 10:29 AM > *To:* [email protected] > *Subject:* Re: Base of riser on placards > > > > So I have the total demand at the BOR and the expected pressure loss from > static with the entire design area flowing. How does a main drain test > simulate this? My understanding of the main drain test is a comparative > analysis of pressure drop as recorded at acceptance from the Contractor's > Above Ground Materials and Test Certificate with the pressure drop at the > time of the test. I presume that original data is what is noted under the > area of the placard for "Supply Data" and is irrelevant regarding the > calculations. > > > > > > > > On Fri, Jul 8, 2016 at 10:16 AM, Steve Leyton <[email protected]> > wrote: > > The information of value at least once a year when you do the main drain > test. Maybe you could add both BOR and Source demands, but I don’t agree > with posting Source data in lieu of BOR. > > > > SL > > > > *From:* Sprinklerforum [mailto: > [email protected]] *On Behalf Of *Todd > Williams > *Sent:* Friday, July 08, 2016 10:15 AM > *To:* [email protected] > *Subject:* RE: Base of riser on placards > > > > I'll ask the unthinkable question, is the BoR demand on the placard > worthwhile? Hydraulic calculations are done back to the effective point of > the flow test. The underground losses, hose demand and sometimes backflow > preventer losses are taken before the BoR. Consequently you cannot compare > the BoR demand to a new public water test and make a valid conclusion > without a full set of original plans and calculations. Wouldn't it make > more sense to put the demand at the water source on the placard? > > Todd G Williams, PE > > Fire Protection Design/Consulting > > Stonington, CT > > 860-535-2080 (ofc) > > 860-608-4559 (cell) > > > > Sent using CloudMagic > <https://cloudmagic.com/k/d/mailapp?ct=ti&cv=6.0.64&pv=8.2> > > > > On Fri, Jul 8, 2016 at 10:21 AM, Ed Kramer <[email protected]> wrote: > > I’ve asked this question in the past and the answers have been all over > the board. > > > > I tend to think the BOR location needs to be consistent from project to > project, whether it’s a single system riser or multiple system risers. In > our part of the universe, most (but not all) backflow preventers are > located inside the building immediately downstream of the underground > flange. I locate the BOR at the underground flange on all systems. By > placing data from that location on the Hydraulic Design Placard, it makes > it easier for someone else to compare the sprinkler system demand to water > supply data. > > > > I believe the intent is to include the combined hose allowance, but got > nothing from the standard to back that up. With a strong water supply (lots > of volume), available pressure while flowing the sprinkler plus hose demand > is going to be virtually the same as pressure available while flowing only > sprinkler demand. But many of the water supplies we work with are marginal. > Removing 100, 250 or 500 gpm combined hose allowance from the water supply > can make a very significant difference in available pressure. So when > comparing sprinkler demand to water supply data, knowing the combined hose > allowance is very helpful. > > > > Respectfully, > > Ed Kramer > > Bamford Fire Sprinkler > > > > > > > > *From:* Sprinklerforum [ > mailto:[email protected] > <[email protected]>] *On Behalf Of *Ben Young > *Sent:* Thursday, July 07, 2016 3:06 PM > *To:* [email protected] > *Subject:* Base of riser on placards > > > > What's the general consensus on the location of the 'base of riser' for > hydraulic placards that everyone uses? See Figure A 24.5 in the 2010 > Edition of 13 and/or 24.5.2 > > I feel its supposed to be at the base of each sprinkler riser (where you > have multiple systems) where it ties into a common header. > > Others in my office think its where the incoming flange comes into the > riser room. > > If you have a vertical riser with a vertical backflow, then these two > points would be the same with either method in my line of thinking. > > Also, is the hose indicated on the placards supposed to be inside hose > only, or combined in and out? I just realized after reading this today > that it could only be referring to inside hose, but I've always put the > combined hose there... > > Thanks, > > > Benjamin Young > > > _______________________________________________ > Sprinklerforum mailing list > [email protected] > > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org > > > > > > -- > > Ron Greenman > > > 4110 Olson Dr., NW > Gig Harbor, WA 98335 > > [email protected] > > 253.576.9700 > > > > A problem well stated is a problem half solved. -Charles F. Kettering, > inventor and engineer (1876-1958) > > > _______________________________________________ > 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
