Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Mass Balance of tank

  1. Feb 15, 2016 #1
    I'll be using a mass balance calc for a tank design at work. We are designing a tank that has an automatic float switch on it, attached to a valve which will start filling the tank when the water level drops below a certain point. This tank is intended to drain quickly (flow rate not known at this time), but the fill rate will not be as large as the discharge rate. I want to have a representative model of the tank so we can ensure it will function properly.

    Anyway, I just want to double check to see if I did this correctly. I think I did, as its relatively simple, but another set of eyes never hurts.

    What I have done so far:
    I'll skip the intro equation sorting, and get to the generic equation below:
    A(dh/dt) = Qin - Qout

    A = Tank area
    h = tank height
    Q = flow rate

    My attempt:
    I moved "A" and "dt" to the right-hand side, and got:
    dh = (Qin - Qout)/A * dt

    I then integrated to get h(t):
    h(t) = [(Qin-Qout)/A] * Δt

    I think this would be correct, as the units leave me with "ft"
    Q (ft3/s) * 1/A (1/ft2) * Δt (s) = ft.
    Last edited: Feb 15, 2016
  2. jcsd
  3. Feb 15, 2016 #2


    User Avatar
    Science Advisor
    Homework Helper
    2017 Award

    So far, so good ! Carry on !
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook