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Thread: Calculating Hydrostatic Pressure

  1. #1
    Join Date
    Dec 2010
    Location
    Portland, OR
    Posts
    20

    Calculating Hydrostatic Pressure

    Can anyone explain to me how to calculate hydrostatic pressure at the bottom of a conical in psi? A rule of thumb would even help. Thanks

  2. #2
    Join Date
    Apr 2010
    Location
    Moorpark Ca, USA
    Posts
    152
    p = ρ * g * h

    p = hydrostatic pressure [bar]

    ρ = specific gravity of the liquid [kg/m³]

    g = acceleration due to gravity [m/s²]

    h = height of the liquid column [m]
    Chris Enegren
    www.enegrenbrewing.com

  3. #3
    Join Date
    Dec 2010
    Location
    Portland, OR
    Posts
    20
    Thanks for the response Chris. I saw that equation and then posted here because I didn't think I knew how to convert that to useful terms in the brewery. I think I almost have it though:

    p = 1 bar = 14.05 psi
    ρ = SG = liquid kg/m3 / water kg/m3, so SG *1000 = kg/m3
    gravity = 9.8 m/s2
    h = m

    p = ρ * g * h

    bar = 1055 kg/m3 * 9.8 m/s2 * 2 m

    bar / 14.05 = psi = 1,471.7 ?????

    Where am I going wrong?

  4. #4
    Join Date
    Dec 2010
    Location
    Portland, OR
    Posts
    20
    Here we go:

    The unit for p is pascal.

    1 pascal = 0.000145038 psi

    Therefore, 2 meter high liquid at 1.055 SG above a conical will have...

    pascals = 1055 kg/m3 * 9.8 m/s2 * 2 m

    20,678 * 0.000145038 = 2.99 psi

    So, correct me if I'm wrong, but to roughly figure out psi at the bottom of a conical:

    PSI = (SG * 1,000) (9.8) (meters of liquid) (.000145038)

  5. #5
    Join Date
    Dec 2010
    Location
    Portland, OR
    Posts
    20
    Easiest:

    PSI = SG * 1.42 * m

  6. #6
    Join Date
    Mar 2003
    Location
    Nashville
    Posts
    600
    about 0.5 psi per foot
    Linus Hall
    Yazoo Brewing
    Nashville, TN
    [url]www.yazoobrew.com[/url]

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