It would really be good if this thread could be shared with the engineering community at large. I STILL get specifications that require a maximum velocity of 20 fps. Very costly, especially when you have a good water supply.
Lamar Vaughn, SET On Tue, Sep 16, 2014 at 12:03 PM, Roland Huggins <[email protected] > wrote: > actually the difference between the results for D-W and H-W does not vary > consistently (alas there is not a linear relationship). To require using > D-W at very high velocities is unnecessarily conservative. At these > velocities the pressure loss is so high that it is self regulating so > typically occurs only is limited sections of the system. With all the > averaging etc that our process entails, why get anal on ONE piece of the > puzzle? Having said that, one could argue that one should account for the > velocity pressure in the discharge calc at high velocities BUT that is > needed only when you really have such velocities (like in a water spray > deluge) verses seeing an assigned value from our process. > > > Roland Huggins, PE - VP Engineering > American Fire Sprinkler Assn. --- Fire Sprinklers Saves Lives > Dallas, TX > http://www.firesprinkler.org > > > > > > On Sep 15, 2014, at 1:56 PM, Damien Shannon <[email protected]> wrote: > > > So purely along the lines of Andy Rooney's 'have you ever wondered why' > :) > > ... FM Datasheet 2-0, while not limiting the allowable velocity, does > > require that when velocity exceed 30ft/sec, that the calculation be > > performed via the Darcy-Weisbach Method rather than the Hazen-Williams. > > Entertainment value only, but would seem that the variance between > results > > in Hazen-Williams versus Darcy-Weisbach become more apparent with higher > > velocities. > > The 30ft/sec limitation (for application of Hazen-Williams calculations) > in > > FM 2-0 is strangely close to the 10m/sec (32.8ft/sec) limitation in EN > > 12845 Rules for Automatic Sprinkler Installations (previously BS 5306). > > > > > > _______________________________________________ > 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
