What tip speed is safe for a shear-sensitive product?

Ask the product owner or read the vendor's curve for that impeller. Many fermentation and polymer products run below about 10 ft/s, while dispersers run far higher. Enter the limit you are given and the share row tells you the margin.

How do I get shaft speed from a gearbox?

Take the output rpm from the gearbox nameplate, or time revolutions with a tachometer. A belt or chain drive ratio also changes it, so measure the agitator shaft, not the motor shaft.

Why is the diameter entered in inches?

Impeller drawings and nameplates usually carry inches, and the model converts to feet with the fixed 12 in/ft factor. It also removes the unit conversion that older sheets asked the user to type.

Does tip speed change when the batch viscosity changes?

No, at a fixed shaft speed and diameter the rim speed is unchanged. Viscosity changes the power the motor draws and the flow the impeller pumps, which is why a viscous batch can overload a drive at the same tip speed.

Process Manufacturing calculator

Agitator Tip Speed Calculator

Convert impeller diameter and shaft speed into tip speed, then compare it with the limit the impeller or product allows. The share and the maximum shaft speed show how much room is left.

What this calculator does

Impeller tip speed from diameter and shaft speed, in ft/min and m/s, checked against your tip speed limit.

Formula used

Tip speed (ft/min) = π × (impeller diameter ÷ 12) × shaft speed
Tip speed (m/s) = tip speed (ft/min) × 0.00508
Tip speed share of limit = tip speed ÷ maximum tip speed × 100
Maximum shaft speed at the limit = maximum tip speed ÷ (π × diameter in ft)

Inputs explained

Impeller Diameter: Impeller diameter from the drawing or nameplate, in inches.
Shaft Speed: Agitator shaft speed from the gearbox nameplate or a tachometer.
Maximum Tip Speed: Your stated tip speed limit for this impeller and product.

How to use the result

Best suited to checking a speed change before trial, comparing impellers at one shaft speed, setting a maximum drive speed.
Tip speed alone does not describe mixing; flow and power depend on the impeller type. A variable frequency drive or belt change alters shaft speed, so re-measure after either.

Current U.S. benchmarks

The producer price index for industrial chemicals stands at 336.006 (BLS, Aug 2026), up 13.3% from a year earlier. Quotes priced off last quarter's material cost miss this move.
The U.S. has 14,543 chemical manufacturing establishments employing about 911,245 workers (Census County Business Patterns, 2023).

Common questions

What tip speed is safe for a shear-sensitive product? Ask the product owner or read the vendor's curve for that impeller. Many fermentation and polymer products run below about 10 ft/s, while dispersers run far higher. Enter the limit you are given and the share row tells you the margin.
How do I get shaft speed from a gearbox? Take the output rpm from the gearbox nameplate, or time revolutions with a tachometer. A belt or chain drive ratio also changes it, so measure the agitator shaft, not the motor shaft.
Why is the diameter entered in inches? Impeller drawings and nameplates usually carry inches, and the model converts to feet with the fixed 12 in/ft factor. It also removes the unit conversion that older sheets asked the user to type.
Does tip speed change when the batch viscosity changes? No, at a fixed shaft speed and diameter the rim speed is unchanged. Viscosity changes the power the motor draws and the flow the impeller pumps, which is why a viscous batch can overload a drive at the same tip speed.

Last reviewed 2026-10-01.