Why cant we just use the hydraulic data plate for the demand needed and add a line for maximum pressure loss allowed through backflow and leave it at that? Then if the backflow is replaced there is a number to work to and you know how much flow is needed if it is measured.
On Fri, Jul 26, 2013 at 5:34 PM, John Denhardt <[email protected] > wrote: > Sounds like a good opportunity for a public input. > > Sent from my Motorola Smartphone on the Now Network from Sprint! > > > -----Original message----- > From: Dwight Havens <[email protected]> > To: "[email protected]" < > [email protected]> > Sent: Fri, Jul 26, 2013 17:57:21 EDT > Subject: Re: SIGN for Backflow Prevention Assembly Forward Flow Test > > Then they ought to say that in the code language. > > Dwight > > > > > ________________________________ > From: John Denhardt <[email protected]> > To: "[email protected]" < > [email protected]> > Sent: Thursday, July 25, 2013 3:07 PM > Subject: RE: SIGN for Backflow Prevention Assembly Forward Flow Test > > > While I do disagree to some extent of what the NFPA 25 committee has done, > Roland statement is correct. I have had numerous discussions with NFPA 25 > committee members where they have stated the intent was to exercise the > device at near system demand. The key word to me was "Exercise". > > John > > John August Denhardt, P.E., FSFPE > Strickland Fire Protection Incorporated > 5113 Berwyn Road > College Park, Maryland 20740 > Office Telephone Number: 301-474-1136 > Mobile Telephone Number: 301-343-1457 > FIRE SPRINKLERS SAVE LIVES - Can you live without them? > > -----Original Message----- > From: [email protected] [mailto: > [email protected]] On Behalf Of Forest Wilson > Sent: Thursday, July 25, 2013 2:42 PM > To: [email protected] > Subject: Re: SIGN for Backflow Prevention Assembly Forward Flow Test > > Here is an email on this topic that Roland addressed in the past: > > Im not going to say it was one of those casual assumptions that all > systems are calculated nor that all risers have placards. The main > thing to keep in mind that the intent is simply to fully EXERCISE the > BFP at what os expected to be the system demand. If no data > available, a discussion with the AHJ is warranted. As for benchmarks, > only the flow is pertinent and pressure is irrelevant. > > Roland > > On Dec 22, 2009, at 2:44 PM, Matthew J. Willis wrote: > > >> > >> On a more important matter: If a system was retrofitted with a > >> backflow, > > and > >> there is no hydraulic calc plaque attached to the riser, and NFPA > >> requires > >> forward flow testing of backflows, how can you conduct the test > >> without a > >> benchmark to test against? > >> > >> What is the recommended practice in this scenario? > >> Forest Wilson > > Sent from my iPhone > > On Jul 25, 2013, at 12:16 PM, Ron Greenman <[email protected]> wrote: > > > Then subjective good flow demonstrates a working valve? If so all the > > numbers bantered around are pretty meaningless. > > > > > > > > On Thu, Jul 25, 2013 at 8:07 AM, Forest Wilson <[email protected] > >wrote: > > > >> No. > >> The intent is not to pitot the output but to exercise the valve. > >> > >> > >> Sent from my iPhone > >> > >> On Jul 25, 2013, at 10:56 AM, Ron Greenman <[email protected]> > wrote: > >> > >>> Forest. What were you flowing to discover these failures? Main drain or > >>> some special test header? Would a sign with the data requested by the > >>> customer that started this thread have had any utility in helping you > >>> discover the problem? > >>> > >>> Then back to that perennial question of what's a "full flow " test and > >> how > >>> do you do one? I think Roland said the intent was to flow an equivalent > >> to > >>> the design discharge criteria. How do you do this? Do we run a pitot > >>> somewhere on the system? Do we catch and measure discharge? If so, from > >>> where? How do we arrange the test port(s)? Do we flow the design area > or > >>> simulate it elsewhere? Do we need results of at least or better flow or > >>> right on the money flow? If not either of those how do we judge? > >>> > >>> Doesn't the hydraulic data plate note the required psi per the calcs at > >> the > >>> BOR and the static? Isn't the difference the residual drop at that > point > >>> relative to the design area? Wouldn't a main drain with good flow at a > >> psi > >>> around the BOR rating, and returning to close to the noted static when > >>> terminated suggest a fully open valve, or an adequately open valve if > the > >>> UG is oversized? In the latter case the partially open valve is > >> equivalent > >>> to fully open for the system I just described. Am I missing something > >> here? > >>> An erroneous a priori? My understanding of hydraulics wrong? Main > drains > >>> are too small to simulate the result of all design area heads flowing > as > >>> the water passes through the BOR? > >>> > >>> > >>> On Thu, Jul 25, 2013 at 7:34 AM, Forest Wilson <[email protected] > >>> wrote: > >>> > >>>> I still have the check valve from a Ames that failed to open. > >>>> It was jammed shut, discovered when I was called out because they > >> couldn't > >>>> do the fire pump test. > >>>> > >>>> In another case, I tested a backflow and it failed (on a Best Buy > >> store). > >>>> I opened the valve up and the check was > _______________________________________________ > Sprinklerforum mailing list > [email protected] > > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org > -- Greg McGahan Living Water Fire Protection, LLC <http://www.livingwaterfp.com> 1160 McKenzie Road Cantonment, FL 32533 850-937-1850 fax 850-937-1852 _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
