# Shut off head, quick estimate

SHUT OFF HEAD, QUICK ESTIMATE S051

The maximum head that the pump can generate with a given impeller diameter and a given horsepower driver.

At shut off the pump would have no capacity. You can estimate the shut off head of a single stage centrifugal pump with the following formulas:

How to estimate the shut off head of an inch size pump running at electric motor speeds.

• At 1750 rpm. Shut off head = Diameter of the impeller squared
• At 3500 rpm. Shut off head = Diameter of the impeller squared x 4
• For other speeds you can use the formula : Shut Off Head = D2 x (rpm / 1750)2

Estimating metric head is a little bit more involved, but it still works:

• Measure the impeller outside diameter in mm. (ie. 250 mm)
• Mark off two places to convert to decimeters. (2,5)
• Square the number. (6,25 )
• For 1450 rpm, multiply by 3 (18,75)
• Add 10 % to your answer (21 meters )

NOTE: For 3000 rpm, you would multiply by 12 instead of 3. Although you can estimate shut off head with these formulas you cannot estimate the pump capacity (gpm or m3/hr). You will need the pump curve that was supplied by the pump manufacturer for that number.

For an indepth explanation of this method, click here.

### Posted

• On February 17, 2018