Calculated systems are indeed a quantum leap forward and provide much better protection for higher demand systems. Just based on the fact that the conversion from pipe schedule to calculated was configured on equal discharge only 2/3 the way into the system instead of the most hydraulically demanding supports the statement that calculated is better.
But just because a portion of a process uses real physic based equations does not equate to the whole process being reality or physic based. Since we have no idea what actual density is hitting the floor, reality stops with the water discharging from the sprinkler (actually even then it is not academically pure due to allowed assumptions in the calculation process). Well the only reality is that the process works to control the fire and becoming overly anal about aspects like area of coverage or distance to wall needs to be discussed not on a physic standpoint but on an enforcement standpoint. Consideration for economical differences between new systems and retrofits is an appropriate consideration for enforcement provided a level of confidence that the reality of fire control can be reasonably shown. It all makes physical sense to me too but it has little to do with physics. Focus on the need for REPEATABILITY. Roland Huggins, PE - VP Engineering American Fire Sprinkler Assn. --- Fire Sprinklers Saves Lives Dallas, TX http://www.firesprinkler.org On May 22, 2014, at 6:54 AM, Brad Casterline <[email protected]> wrote: > "The designed system has little to do with physics or reality." > > Roland, I did not want to take your statement out of context completely, > because I know how much that hurts sometimes, so I did not trim this thread. > > I am always trying to quantify things as best I can so here is my shot: > > At the time calculations were being accepted into NFPA 13 the 'reality' was > that pipe scheduled systems had worked for 90 years. > In order for proposed changes to be accepted (then and now I guess) an > equivalency of some sort had to be shown, and that is where the 'physics' > came in, along these lines: given a certain water supply, what flows will a > scheduled system produce? Now, for the sake of economy, how much can we beef > it up here and slim it down there and still get equivalent results; mix a > little fluid mechanics theory with a lot of water flow measurements and... > BOOM! the density/area curves where born. > > So calculated systems using the density/area curves are nothing more than > reconfigured pipe scheduled systems at their roots. > > This is just my current understanding, and if it is mostly correct, it makes > real and perfect physical sense (to me anyway) ;) > > Brad Casterline, SET > > ps- I think calcs were a quantum leap in fire sprinkler design, and I think > the future WILL involve 'fire having something to do with it'. _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
