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 > >
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