Are we once again worrying about the difference between 0.003 psi and 0.004 psi?
If I recall the number we're trying to compare demand against supply is based on a formulae with a constant (average), an average C-factor of deterioration based on variable conditions over many years, a nominal diameter, and a velocity pressure determined by holding a pitot in a stream of water that's trying to rip the pitot out of your had while you take an average reading from a bouncing gauge that has a +/– built in. Then we do the math, round to the nearest 50 gpm, and apply it to a graph so small that the width of the line has an effect. And as Brad said the fitting is calculated into the K factor of the sprinkler. And as someone else noted the flexible drop is a drop, not a fitting. It has a fitting the sprinkler screws into. It also has a friction loss value that has to be an average as it doesn't take the curves into account. And do we calculate the gain from the elevation change? On Fri, Oct 28, 2016 at 8:33 AM, Brad Casterline <[email protected]> wrote: > Here is my original reply, for what it's worth... > > > > > > Russell, > > > > My understanding is we do not have to figure the loss for the fitting the > > sprinkler is in because when the K Factor was being established it was in a > > fitting. > > NFPA 13 (2016) 23.4.4.8.1 (9) confirms that. > > But it's a good question because we're supposed to use a manufacturer's > > published loss if they have one. > > So would it make sense to, if the published loss is greater, subtract the > > loss shown in 13, and include that difference? > > > > Brad > > > > > ------------------------------ > > *From:* Sprinklerforum [mailto:[email protected]. > org] *On Behalf Of *Brad Casterline > *Sent:* Friday, October 28, 2016 10:19 AM > *To:* [email protected] > *Subject:* RE: Hydraulic losses when using a Mechanical Tee on Sprinkler > Outlet > > > > Here is the e-mail I sent to our in-office guy whom submits questions to > NFPA: > > > > > > ***** > > "From NFPA 13- 2016 > > > > > > *23.4.3.1.1 *Table 23.4.3.1.1 shall be used to determine the > > equivalent length of pipe for fittings and devices unless manufacturer’s > > test data indicate that other factors are appropriate. > > > > *23.4.4.8.1* > > (9) Friction loss shall be excluded for the fitting directly > > connected to a sprinkler. > > > > > > A 1" tee in the table is 5' equivalent length. > > A mechanical tee with 1" outlet is 11' equivalent length. > > > > If the sprinkler is directly attached to the mechanical tee do we still > exclude it?" > > ***** > > > > > > When we got the recent response Gregory pasted, I asked the guy for the > exact wording of the submitted question, but since submitting a question > on-line 'disappears' once submitted, it was not available. He said he > reworded mine a little, but thinks the last line (which is what this is all > about) was clear. > > > > Personally, I like my original reply to Russell, but I'm just a Tech, so > there's that :) > > > > Brad > > > > > ------------------------------ > > *From:* Sprinklerforum [mailto:[email protected]. > org] *On Behalf Of *Russell & Carol Gregory > *Sent:* Thursday, October 27, 2016 10:01 PM > *To:* [email protected] > *Subject:* RE: Hydraulic losses when using a Mechanical Tee on Sprinkler > Outlet > > > > Ken, and others, > > We have been excluding the loss for a welded outlet or a mech tee when a > sprinkler is directly attached. If the outlet is to feed a pipe (regardless > of length) then the standard loss for a branch on tee would be used, > however if the Manufacturers Data Sheet states that the loss in a clamp tee > is greater than the loss in Table 23.4.3.1.1 (NFPA 13 2016) for a side > outlet of tee, THEN the ADDITIONAL LOSS shall be included. I think they > should say the Higher EQL Loss should be used so you don’t use less than > the Table Loss. > > > > Here is a recent NFPA Response to a similar question; > > > > Table 23.4.3.1.1 is required to be used to determine the equivalent length > > of pipe for fittings and devices unless manufacturers' test data indicate > > that other factors are appropriate. In your situation since the > manufacturer > > specifies an equivalent length of 11 feet, you are required to use 11 feet > > for the equivalent length. > > > > In regards to Section 23.4.4.8(9) of the 2016 edition of NFPA 13, if an > > extension is used with a tee, that tee must be included in the hydraulic > > calculations. The allowance to use an extension is restricted to sprinklers > > with a relative low discharge volume. They will most likely be used for > > minor adjustments to interface with the ceiling. > > > > This answers some of the other Forum responses to my questions but does > not answer my problem. > > > > What I would like to see is a practical flow test done with a K36 (us k25) > head and see if there is a significant difference between welded outlet, > threaded tee and clamp tee. Does anyone know if this has been done??? > > > > Our AHJ has asked for the full loss to be included and this will nearly > double the pressure required at a K-36 sprinkler from 345kPa(50psi) to > around 600kPa(90psi), if clamp tees are used. There is quite a variation > between Brands for the stated EQL. > > Makes life difficult if site staff change from welded to mechanical > fittings and then buy a variety of brands!!!!! > > > > Thanks for the responses. > > Russell Gregory > > > > > > *From:* Sprinklerforum [mailto:[email protected]. > org] *On Behalf Of *Parsley Consulting > *Sent:* Friday, 28 October 2016 3:56 AM > *To:* [email protected] > *Subject:* Re: Hydraulic losses when using a Mechanical Tee on Sprinkler > Outlet > > > > Russell, > Mark and Todd are both correct. > If the sprinkler is directly attached to the fitting, in this case the > welded outlet or mechanical tee, the friction loss through that fitting is > excluded from the hydraulic calculations, per NFPA 13, 23.4.4.7.1(9). I > don't know that I've ever had a set of calculations sent back with a > comment that I didn't include the friction loss equivalent for the welded > outlet or mechanical tee which was directly attached to the sprinkler. > Todd's comment is valid as well, however it's worth noting, I believe, > that when you're designing a system with flexible drops you must account > for the equivalent length of the device, using the manufacturer's data. My > own experience has been that those values are substantial. > sincerely, > > > *Ken Wagoner, SET * > > > *Parsley Consulting 350 West 9th Avenue, Suite 206 Escondido, California > 92025 * > *Phone 760-745-6181 <760-745-6181> **Visit our website > <http://www.parsleyconsulting.com/> * > > On 10/27/2016 1:30 AM, Russell & Carol Gregory wrote: > > I posted a message on this subject early this month but only received one > reply(thanks Brad). This was surprising as I thought it was a serious > problem if the full EQL for tee had to be added to calculations. Especially > if the change was made on-site after design had been completed with welded > outlets. > > So my query is as follows; > > > > When calculating a Range Pipe with welded threaded outlets for sprinklers > it is not necessary to include a loss for the water leaving the range pipe > and entering the sprinkler. The total pressure is assumed to apply to the > sprinkler orfice. > > This means that a 80nb pipe with a 25nb outlet and a k36 sprinkler does > not have an additional loss added for the outlet fitting. > > > > If I change my design and fabricate the 80nb range pipe with 80 x 25 > Mechanical Tees for the Sprinkler outlet do I have to apply an additional > loss factor for that fitting? The published EQL for Mech tees varies > greatly between brands,( 0.8m up to 2.4m). This means a head pressure of > 345kPa would need around 600kPa in the range if this additional loss is > added. > > > > Questions; > > 1. Is it common practice in USA to use 80 x 25 clamp/mechanical > tees for attaching large bore Storage Sprinklers directly to 80nb range > pipes? > > 2. Is it common practice to add in an additional loss for the clamp > tee, in the hydraulic calculation, where the sprinkler is directly fitted > to the tee outlet? > > > > I would appreciate the Forum members advise as to what is the standard > practice in the USA. > > > > Russell Gregory > > Christchurch > > New Zealand > > > > e-mail [email protected] > > > > > > _______________________________________________ > > 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 > > -- Ron Greenman 4110 Olson Dr., NW Gig Harbor, WA 98335 [email protected] 253.576.9700 The Universe is monstrously indifferent to the presence of man. -Werner Herzog, screenwriter, film director, author, actor and opera director (1942-)
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