And that folks is a good summary and an even better ENDING POINT. This thread has more than run its course so if any one wants to continue beating on it, do it as private emails. The other 99% will greater appreciate it.
Thanks, Roland Roland Huggins, PE - Senior VP Engineering American Fire Sprinkler Assn. Dallas, TX http://www.firesprinkler.org <http://www.firesprinkler.org/> Fire Sprinklers Saves Lives > On Feb 21, 2017, at 8:00 AM, Steve Leyton <[email protected]> wrote: > > Okay, as respectfully and diplomatically as possible, stop it. Just stop. > > The purpose of a standpipe system is to deliver water to firefighters for use > in the most challenging and potentially life-threatening systems imaginable. > They need a USABLE water supply at adequate flow and pressure, with a > REASONABLE safety factor. Adequate is defined by fire-fighting tactics and > the prescriptive code provides a framework on which a design can be hung and > tailored to suit the needs of the responding fire department(s). The final > design must address those needs, and in the 17 years (6 published editions of > NFPA 14) I’ve been on the committee, we have never entertained a proposal or > even a conversation regarding adequacy of the current requirements for Class > I standpipe flow rates. Pressures yes, flow rates no. > > “K” means “constant” in mathematical terms. A constant is, “a special > number, usually a real number, that is significantly interesting in some > way". Pi is a constant. The K-values given to sprinklers are just that: > constant coefficients of flow that will yield discharge rates that increase > or decrease with the applied pressure. But a valve is not a fixed state > device and as such, attempts to assign a constant value are nothing more than > mental masturbation because the “K” is only relative to that setting on the > valve, i.e. its variable state of wholly or partially open or closed. The > idea that we could or should calculate 1,100+GPM from a hose valve at 100 PSI > is silly because no firefighting team will use that kind of water supply > threw small diameter attack lines. > > Do you think that, because it’s theoretically possible we should calculate > 1,000 from each of the two most remote outlets then at 1,000 for additional > standpipes? What would we prove as a maximum flow rate – 2,000 + 1,000, + > 1000 in a sprinklered building? There are myriad reasons why such high > flow rates are superfluous and why firefighters won’t use them; I emphasize > that the basic flows and starting pressures (i.e. 150 PSI at the inlet) that > are prescribed in NFPA 14 are derived from tactical firefighting standards > like NFPA 13E and the IFSTI Engineer’s Guidebook. My energy about this is > based on my concerns that even at the level of conversation, people will try > to apply ideas that are not grounded in codes or good practices – proven and > widely accepted good practices. > > If you need to figure out a K-factor for a hose valve (and Vince had a reason > for asking), consult the manufacturer and acquire a friction loss chart for > the valve in question. They all have one, but sometimes you have to beat on > their tech services people to get a look. Add that to the inlet pressure > you’re working with and solve for K and whatever flow rate you may have to > prove. If you think you need a K to determine the required inlet pressure > at a certain flow, you’re working backwards because the critical metric is > residual PSI at the tip. You need to prove the right flow at adequate > pressure to make the tip work, and that pressure can vary widely depending on > make/model of nozzle, diameter of the attack line(s) and of course, flow > rate. > > MY OPINION ONLY, > Steve L. >
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