The "jet effect" were the AHJ's words, the man can barely read a set of calculations, I wasn't going to get into physics with him.
-----Original Message----- From: bcasterline <[email protected]> To: sprinklerforum <[email protected]> Sent: Thu, May 31, 2018 3:57 pm Subject: Re: Ceiling Grids and Flex Drops Newton's Third Law?After I fry this fresh cloud based sprinkler applet I'll check your math Allan and respond off Forum if need be. :)You know I worked with the inventor of the Hose Monster? He told me when where and how he got the idea. I'm the Forest Gump of this industry:*worked with inventor of sprinkcad*worked with inventor of autosprink*worked (and still do) for the first person to print the first density/area curves for TC consideration.You can see a pic of him here:https://www.fsc-icalc.comBradQuoting AKS-Gmail-IMAP <[email protected]>:> So what is this jet effect that is going to lift the sprinkler? The > forces on this sprinkler are going to be the end pressure force and > any momentum change force.>> Lets say this is a 5.6k sprinkler having a .438” diameter orifice. > The orifice area is about 0.1507 square inches. That is about 1lb > for 7 psi and about 12 lbs for 80 psi since those pressure numbers > are gage pressure referenced from atmosphere pressure. The orifice > end pressure force must be why we have the last sprinkler surge > restraint rule where there is not much piping for counter balance.>> Now what is the momentum change? The water comes streaming out the > nozzle and slams into the deflector that is connected to the nozzle. > There is a canceling out. Then the water changes momentum to go > radially. Lets say that is equal in all directions. So the radial > momentum changes cancel each other. Think of a Hose Monster. The > momentum change situation is not the same as that of hose nozzle > stream needing some beef to hold it.>> It would not take much to demonstrate this. Take a flex drop and > operate it with an open sprinkler and compare to operating it also > with a busted off sprinkler that has no deflector and arms. Pick a > nice hot day to do this.>>>> On May 30, 2018, at 10:59 AM, Richard Mote >> <[email protected]> wrote:>>>> I have a AHJ <> that is questioning the use of Flex Drops >> especially the Victaulic ones. He says that they are so flexible >> that when a sprinkler goes off the jet effect is going to lift the >> sprinkler up through the ceiling. I told him that the drops are >> mechanically attached to the ceiling grid and in order to lift up >> they would have to lift the entire weight of the ceiling grid, >> ceiling tiles, the lights and HVAC diffusers. His answer prove, it >> either by letter from the manufacturer or from someone a lot higher >> up the food chain than either he or I am. Or something specific in >> NFPA <> 13 that says he is wrong.>>>> Richard Mote>> Design Manager>>>> W: 877.324.ROWE · F: 570.837.6335>> PO Box 407 · 7993 US Route 522, Suite 1 · Middleburg, PA 17842>> 505 A Cornerstone Court · Hillsborough, NC 27278>> RoweSprinkler.com · [email protected] >> <>_______________________________________________>> Sprinklerforum mailing list>> [email protected]>> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org_______________________________________________Sprinklerforum mailing [email protected]http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkler.org
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