What is the height above the water main, above which the water will not flow?

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    Diane Colucci (Edited )

    you used 2.3 in this question. When would you use .433? 

    i have p = .433 x height

    i think im getting confused about when to use .433 and when to use 2.3 

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    Diane Colucci

    If a water line has 35 psi of pressure what is the max height of a faucet needing 12psi above grade?

    p=.433 x height

    35-12=.433 x height

    53.12 = height

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    Michael Ermann

    1/2.33 = 0.433. . . It's like converting km to miles and back. . . you use one number (1.6) to convert miles into km and the inverse of that number (1/1.6 = 0.62) to convert km back to miles. Or pick your favorite foreign currency: you use one number to convert to dollars from the foreign currency and the inverse of that number to convert the other way.

    So for plumbing, we use one number for multiplying times the height to get pressure. . .  p=.433 x height

    and the inverse for multiplying times pressure to get height. . .  height = 2.3 x p

    It's a bit more intuitive to convert height to pressure. . . if you hold water in a water tower 100 feet above a fixture, we can understand how the pressure may increase if we increase the height of the water tower to 200 feet above a fixture. . . it's a bit unintuitive sometimes to think of converting pressure to height, but if water enters a building at some pressure, let's say 60psi, and you run that water up an uncapped pipe, moving up through the floor plates, at some height high enough, the pressure will be gone such that, if you stick your finger inside the open end of the uncapped pipe and pull it out, your finger will be dry. Not enough pressure to push the water past a point a few floors down. How high can 60psi move up before the pipe gets dry?

    height = 2.3 x p

    height = 2.3 x 60'

    height = 138'

    So if the floor you're standing on is 175' high, and you put your finger inside the open pipe, it will be dry. But if you drilled a hole in the same pipe at 100' high, you'd watch water leak through the hole.

     

     

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    Diane Colucci

    how would you calculate the pressure at a certain height along the pipe?

    if the water pressure entering the building is 60psi & it enters the building @ + 0'-0" what would the pressure be on the second floor with finish floor @ +10'-0" if the pipe entered the sink @ 2'-6" high

    p=.433 x 12'-6" 

    p=5.41

    p= 60 - 5.41 = 54.59??

    sorry i think i got away from what you were originally asking

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    Michael Ermann

    You got it, Diane!

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    Diane Colucci

    Awesome! This post was great thanks for sharing. 

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