Related Resources: calculators

Spherical Tank Draining Time Formulas and Calculator

Fluids and Flow Engineering and Design
Hydraulic and Pneumatic Design and Engineering
Pressure Vessel Engineering and Design

Draining Time for Spherical (Sphere) Tank Formulas and Calculator

Horizontal Tank Drain From Bottom

Spherical (Sphere) Tank Drain From Bottom

t = ( 0.083 π h1.5 [ D - 0.6 h ] ) / ( Cd An )


t = time to empty in seconds,
D = diameter of the sphere, ft,
h = height of liquid in the cylinder, ft,
Cd = Discharge coefficient,
0.61 for sharp-edged orifice
0.8 for short flush mounted nozzle
0.98 for rounded orifice
An = Cross-sectional area of drain opening (orifice / nozzle) based on ID of orifice / nozzle, ft2 ,
An = π/4 ( d / 12)2


Reference: Section 5, Chemical & Process Plant Engineering
Standard Handbook of Engineering Calculations, 4th Edition, Tyler G. Hicks