Published by Engr. Salah Ud Din, Deputy Director at Pakistan Council of Research in Water Resources in Academic
how can be determine
the emptying time of Water storage tank sizing 18m x 18m x 2.4m with
inflow rate of 4lps when inflow and outflow ends at the same time. The
outlet is 6 inch gate valve
thank you!
Category: Academic
Hi,
I think the comparison between inflow and outflow is quite large, hence with Qout >> Qin with Qout is estimated using this formula:
Qout=mu*A*sqrt(2*g*h)
you can neglect the inflow (Qin) and use the following formula:
t=[(2*A0)/(mu*A*sqrt(2*g))] * (sqrt(h1) - sqrt(h2))
where A0 is your tank cross section (which is constant with respect to tank height I assume), mu is orifice outlet coefficient or gate valve coefficient in this case, g is gravitational acceleration, h1 and h2 is the water level before and after (in this case h2 is 0 since it will be emptied).
In case you want to include the Qin, you need to use another approach since it involves tank/reservoir storage equation. Also another treatment is needed if the areal cross section of the tank is not constant e.g. cone shaped.
Published by Muhammad Alfalah Fauzi, CFD Engineer Intern at Institut für Wasserbau und Technische Hydromechanik (IWD) - TU Dresden
you might find this calculation useful
Published by Jibok Chatterjee
Thank you very much
Published by Engr. Salah Ud Din, Deputy Director at Pakistan Council of Research in Water Resources
The tank will attain a level around 5 hours of commencement of draining at which the cover over an assumed bottom 6 inch outlet will be inadequate to make the outlet run full. At this point if the inflow rate is regulated to reduce to zero, tank runs out very soon thereafter.
Published by Vasudev Shirahatti, Mr.
See attached PDF
Published by Miguel Angel Pavon Gutierrez, Data and Mapping Solutions Lead at Texas Water Development Board
Where At is the area of the tank (18 m X 18 m)
Ao is the cross area of the open valve
g is gravity and
Cd is the coefficient for the tipe and size of valve, I believe is 3076, see https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjs0p2jq7DuAhUlnq0KHaK9D4cQFjAAegQIBRAC&url=https%3A%2F%2Fglobalsupplyline.com.au%2Fwp-content%2Fuploads%2F2014%2F10%2FGate-Globe-Check-Valves-Flow.pdf&usg=AOvVaw1sSUMuyRoM9SuVUF7yN93K
Published by Miguel Angel Pavon Gutierrez, Data and Mapping Solutions Lead at Texas Water Development Board
t= integral from Z2 (2.4 m) to Z1 (0m) of At(sqr z1 - sqr z2) / ((CdAo sqr 2gz) - 4)
Published by Miguel Angel Pavon Gutierrez, Data and Mapping Solutions Lead at Texas Water Development Board