# Centrifugal pump having highest specific speed

Q.  Which of the following centrifugal pumps has higher specific speed than the others?
- Published on 16 Sep 15

a. Axial flow
c. Mixed flow
d. All have same specific speed

#### Discussion

• Katey kano   -Posted on 05 May 17
i am preparing for an interview for Mechanical Technician (Rotating Equipment) in a company that process and deliver natural Gas. i want to be helped with interview tips and answers.
• Pankaj   -Posted on 14 Oct 15
The centrifugal pumps classified on the basis of their specific speed are as follows:

2. Axial flow pump

3. Mixed flow pump

The specific speed (Ns) can be defined as the speed of geometrically symmetrical pump in all respect of actual pump which delivers 1 m3/s of discharge under a head of 1 m.

Ns = (N √Q) / H3/4

Where,

N = speed, rpm

Q = Discharge, m3/s

Specific speeds of pumps

- Radial flow pump: Specific speed = 10-80

- Mixed flow pump: Specific speed = 80-160

- Axial flow pump: Specific speed = 160-450

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