Lay off the home 'shine. Yes. A single sprinkler activating is something I would refer to as an emergency.
Travis Mack, SET MFP Design, LLC "Follow" us on Facebook: https://www.facebook.com/pages/MFP-Design-LLC/92218417692 Send large files to MFP Design via: https://www.hightail.com/u/MFPDesign Sent from my iPhone > On Jan 17, 2017, at 7:01 PM, Brad Casterline <[email protected]> wrote: > > But if only one head activates, there is not much of an emergency, no? > > Brad > >> On Jan 17, 2017 7:53 PM, "Timothy Goins" <[email protected]> wrote: >> Fine and good into you have a fire with only one had that activates. >> >> Therefore I say unto you, Take no thought for your life, what ye shall eat, >> or what ye shall drink; nor yet for your body, what ye shall put on. Is not >> the life more than meat, and the body than raiment? >> MAT 6:25 >> >> Jesus answered, Verily, verily, I say unto thee, Except a man be born of >> water and of the Spirit, he cannot enter into the kingdom of God. JHN 3:5 >> >>> On Jan 17, 2017, at 3:16 PM, Steve Leyton <[email protected]> >>> wrote: >>> >>> Okay, great and wonderful but you what that does is flatten the curve and >>> potentially makes higher flow rate residual pressures plot HIGHER than they >>> would otherwise be. Soooooooo … as a designer-of-record charged with >>> (among myriad other things) anticipating worst case scenario, methinks it >>> makes sense to keep as much tilt in that flow data curve as possible. >>> >>> >>> >>> Steve L. >>> >>> (My opinion only, based on numerous cases served as an expert witness and >>> somebody who buys a lot of liability insurance every year.) >>> >>> >>> >>> From: Sprinklerforum >>> [mailto:[email protected]] On Behalf Of >>> Dewayne Martinez >>> Sent: Tuesday, January 17, 2017 1:13 PM >>> To: [email protected] >>> Subject: RE: Static pressure after backflow preventer >>> >>> >>> >>> Ames got back to me and said “Yes there is a pressure loss at static flow. >>> It will depend on which type backflow youre looking at. A RPZ will usually >>> show a 10-15 PSI drop. A double check is usually 8-10.” >>> >>> >>> >>> >>> >>> From: Sprinklerforum >>> [mailto:[email protected]] On Behalf Of Brad >>> Casterline >>> Sent: Thursday, January 12, 2017 12:51 PM >>> To: [email protected] >>> Subject: RE: Static pressure after backflow preventer >>> >>> >>> >>> Matt, >>> >>> >>> >>> I think your example of sliding friction is excellent. Pressure is force >>> divided by area, and force is mass times acceleration. >>> >>> With sliding friction the force required to give a mass an acceleration is >>> greater than the force required to keep it going a constant velocity. >>> >>> With fluid friction viscosity comes into play and is actually related to >>> sliding friction in that the constant force required to slide a steel plate >>> across the surface of a fluid, imparting a certain constant velocity to the >>> plate is a measure of the viscosity of the fluid. >>> >>> >>> >>> But the question is regarding friction loss when the flow is 0 GPM, and at >>> 0 GPM the velocity of the water = 0. >>> >>> Near the end of what I pasted you see: >>> >>> mgh=1/2mv^2. >>> >>> This is the Conservation of Energy formula for going from Potential Energy >>> (static), to Kinetic Energy (residual). >>> >>> In a closed system no mass is gained or lost (it is the same on both sides >>> so it cancels out), so, >>> >>> h=v^2/2g, and, >>> >>> v=SQRT(2gh). >>> >>> But if the velocity is 0 on both sides the only way to get a different >>> force measurements is with different h measurements (elevations). >>> >>> >>> >>> I know you and others know all this, so please excuse my didactic tone. >>> >>> >>> >>> Brad >>> >>> >>> >>> <image001.jpg> >>> >>> <image002.jpg> >>> >>> >>> >>> From: Sprinklerforum >>> [mailto:[email protected]] On Behalf Of Matt >>> Grise >>> Sent: Thursday, January 12, 2017 6:33 AM >>> To: [email protected] >>> Subject: RE: Static pressure after backflow preventer >>> >>> >>> >>> Of course – if you are super close to a pressure limit – the BFP might also >>> lock in some unusually high pressure spike that occurs in the system. Then >>> the sprinkler system could sit around locked at a pressure that is greater >>> than even the typical measured static. >>> >>> >>> >>> Matt >>> >>> >>> >>> >>> >>> From: Sprinklerforum >>> [mailto:[email protected]] On Behalf Of Matt >>> Grise >>> Sent: Thursday, January 12, 2017 6:30 AM >>> To: [email protected] >>> Subject: RE: Static pressure after backflow preventer >>> >>> >>> >>> Just to think out loud – I don’t have a perfect understanding of how very >>> low flow works through backflows… but: >>> >>> >>> >>> It seems like the system static that is locked in is usually pretty close >>> to the flow test static. I wonder if the noticeable pressure loss to >>> initially open the BFP, that goes down once flow starts, if that pressure >>> drop might approach zero as the flow goes from positive back to zero. >>> >>> >>> >>> That is – the pressure drop seen at a flow that is just barely over zero >>> depends on whether you are approaching that flow from zero, or from [more >>> than zero]. >>> >>> >>> >>> For example: if you slide a block across a table – the force it takes to >>> move the block at a very low speed will depend a lot on whether you start >>> from a standstill, or a faster speed. (that illustrates a different >>> principle, but shows how the approach could change) >>> >>> >>> >>> Thoughts? >>> >>> >>> >>> Matt >>> >>> >>> >>> From: Sprinklerforum >>> [mailto:[email protected]] On Behalf Of Roland >>> Huggins >>> Sent: Wednesday, January 11, 2017 6:07 PM >>> To: SprinklerFORUM >>> Subject: Re: Static pressure after backflow preventer >>> >>> >>> >>> I'm flying by the seat of my pants (with no lights) but until I prove to >>> myself otherwise (or am beat into submission by the technical committee), I >>> don’t see why we should beat ourselves up and default to what ever seems to >>> be the most conservative. Our supply curve is a straight line relationship >>> from static to some lower residual pressure. We now incorporate a device >>> that has a crazy high initial pressure loss that then drops back into a >>> more normal curve. In looking at SYSTEM DEMAND are we well served by >>> ignoring the actual available pressure that was otherwise lost due to >>> accounting for a wiggle at the front end. >>> >>> >>> >>> For now, I’ll stick with my mantra: Lead the way, Mr. Custer. I’m right >>> behind you. >>> >>> >>> >>> >>> >>> Roland Huggins, PE - Senior VP Engineering >>> >>> American Fire Sprinkler Assn. >>> >>> Dallas, TX >>> >>> http://www.firesprinkler.org >>> >>> >>> >>> Fire Sprinklers Saves Lives >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> On Jan 11, 2017, at 12:27 PM, Dewayne Martinez >>> <[email protected]> wrote: >>> >>> >>> >>> I have used the static without the backflow loss in the past but I noticed >>> with the SprinkCad software I am running it uses the mfg curves and it was >>> showing less static than I had figured. If I take into account the BFP >>> loss I can eliminate 6 pressure reducing hose valves…..Looks like I will >>> err on the side of caution and design them in. >>> >>> Thanks, >>> >>> Dewayne >>> >>> >>> >>> >>> >>> _______________________________________________ >>> 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 >> > _______________________________________________ > 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
