Impeller Pumping Rate & Tank Turnover Calculator
Calculate primary impeller volumetric pumping discharge (GPM and m³/hr), flow number (Nq), tank liquid turnover time, and bulk circulation velocity.
Impeller Geometry & Flow Number
Pumping Rate & Tank Turnovers
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Frequently Asked Questions
What is the Impeller Flow Number (Nq)?
The Flow Number (Nq = Q / (N * D³)) is the dimensionless volumetric pumping coefficient of an impeller. It represents how many impeller volumes of liquid are pumped per shaft revolution. High-efficiency axial hydrofoils typically have Nq between 0.50 and 0.60, while pitched blade turbines range from 0.75 to 0.85.
What is the difference between primary pumping rate and total tank circulation?
Primary pumping rate (Qp) is the direct liquid jet expelled through the swept perimeter of the impeller blades. As this high-velocity discharge moves through the vessel, it drags and entrains surrounding stagnant fluid via shear, generating total tank bulk circulation (Q_tot) roughly 1.8 to 2.2 times greater than Qp.
What turnover frequency is required for solid blending vs heat transfer?
Simple liquid blending and storage requires 1 to 2 tank turnovers per minute. Effective vessel jacket heat transfer requires 2 to 4 turnovers per minute. Complete solids suspension and crystallization typically demand 4 to 8 turnovers per minute.