answersLogoWhite

0

Specific speed (Ns) is a non-dimensional design index used to classify pump impellers as to their type and proportions.

It is defined as the speed in revolutions per minite at which a geometrically similar impeller would operate if it were of such a size as to deliver one gallon per minute against one foot of head.

The formula used to determine specific speed is

Where

N = Speed of Pump in RPM

Q = Capacity in gpm at the best efficiency point

H = Head per stage in feet at the best efficiency point

The specific speed determines the general shape or class of the impeller. As the specific speed increases, the ratio of the impeller outlet diameter, D2, to the inlet or eye diameter, Di, decreases. This ratio becomes 1.0 for a true axial flow impeller.

Low specific speed - Radial flow Impeller.

Medium specific speed - Mixed flow Impeller.

High specific speed - Axial Flow Impeller.

User Avatar

Wiki User

13y ago

Still curious? Ask our experts.

Chat with our AI personalities

EzraEzra
Faith is not about having all the answers, but learning to ask the right questions.
Chat with Ezra
JordanJordan
Looking for a career mentor? I've seen my fair share of shake-ups.
Chat with Jordan
TaigaTaiga
Every great hero faces trials, and you—yes, YOU—are no exception!
Chat with Taiga

Add your answer:

Earn +20 pts
Q: What is the significance of specific speed?
Write your answer...
Submit
Still have questions?
magnify glass
imp