Agitated Tank Blend Time & Homogeneity Calculator

Estimate 95% macro-mixing blend time (θ95) in turbulent baffled stirred tanks using the Grenville correlation and Norwood-Metzner equations.

Tank & Agitator Dimensions

Tank Diameter T (m):

Liquid Height H (m):

Impeller Diameter D (m):

Agitator Speed N (RPM):

Turbulent Power Number Np: PBT: 1.27 | Hydrofoil: 0.35 | Rushton: 5.2

Number of Standard Baffles:

Homogeneity & Turnover Times

95% Blend Time (θ95):

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Impeller Revolutions to 95%:

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Liquid Volume:

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D/T Geometry Ratio:

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Estimated Turnover Cycle Time:

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Frequently Asked Questions

What is the 95% blend time (θ95) in an agitated vessel?

The 95% blend time is the time required from tracer addition for local concentration variations anywhere in the vessel to remain within ±5% of the completely mixed equilibrium concentration.

How does impeller diameter affect blending time?

Blend time is inversely proportional to the square of impeller diameter (T/D)². Increasing impeller diameter from D/T = 0.25 to D/T = 0.40 cuts blending time by more than half at constant rotational speed.

Why do unbaffled vessels have drastically longer blend times?

Without vertical wall baffles, fluid swirls in solid-body rotation around the central vortex with minimal top-to-bottom circulation, causing tracer to stay trapped in stagnant toroidal zones for minutes.