Quadratic curve operating flow calculator

Equate fitted pump head H_0−aQ² and system head H_static+KQ² within their valid operating range.

Units

Q = \sqrt{\frac{H_{0} - H_{\text{static}}}{a + K}}

Calculator

Enter the values you know and leave one box empty. Calculate finds the empty one, the result or any input.

Given

Q = \sqrt{\frac{100 - 20}{0.0003 + 0.0002}} = 400

Symbol	Meaning	Unit
$Q$	operating flow	gpm
$H_{0}$	pump shutoff head within fitted curve	ft
$H_{\text{static}}$	system static head	ft
$a$	pump-curve quadratic coefficient	ft/(gpm)^2
$K$	system quadratic coefficient	ft/(gpm)^2

Symbol	Meaning	Unit
$Q$	operating flow	L/s
$H_{0}$	pump shutoff head within fitted curve	m
$H_{\text{static}}$	system static head	m
$a$	pump-curve quadratic coefficient	m/(L/s)²
$K$	system quadratic coefficient	m/(L/s)²

Results are estimates for study and screening. Check the inputs, units and assumptions before you use them for design, billing or contract decisions.