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]] 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 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
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