JavaScript is off. Reference tables, cheat sheets and guides below are fully readable. The calculators, search and navigation need JavaScript — everything still runs in your browser, nothing is sent anywhere. Browse all tools

Tank Drain Time

Draining slows as the head falls, so the time is not linear: t = (A_tank/(C_dA_o√(2g)))·2(√h₁ − √h₂). Halving the level does not halve the time.

Tank cross-section (m²)

Orifice diameter (mm)

Start level (m)

End level (m)

Discharge coefficient Cd

Drain time

—

Drain time

—

Initial efflux velocity

—

Vented tank, constant cross-section, no inflow. A closed tank needs a vent or the drain stalls under vacuum.

A helper, not a substitute for engineering judgment. Verify against the governing standard.