Elevation Gain formula

[doingwhat]

Provide a calculation showing that the 5’-4” long branch line and drop, including the elevation gain from the
cooler ceiling to the existing branch line at .445 X 100 = 45.5gpm, is less than the staring pressure for the roof
level sprinklers at .5 X 11’-6” X 8’ = 46gpm. If the friction loss exceeds the elevation gain, provide a hydraulic
calculation for the cooler.

I figured out i should use the hazen williams formula for the arm over
(4.52 x (45.5)^1.85 )/ ((120)^1.85 x (1.049)^4.87 ) = 0.57 psi

so which formula i should use for the elevation gain?

 

[LittleInch]

2.31 ft = 1 psi of water on earth.

Multiple sites will tell you this.

I couldn't follow the system from your description - an isometric drawing would be useful.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[TravisMack]

aka 0.433 psi / ft for elevation change. You should be doing this basic check for all TI systems. At least that is what I do. It's just a way to make sure we can get enough wet stuff to the hot stuff.

Travis Mack, SET, CWBSP, RME-G, CFPS
MFP Design, LLC

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