Specific Speed of Pump Calculator

Specific Speed of Centrifugal Pump Formula:

\[ N_s = \frac{\omega \cdot \sqrt{Q}}{H_m^{3/4}} \]

Specific Speed of Centrifugal Pump (Ns):

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1. What is Specific Speed of Centrifugal Pump?

The Specific Speed of Centrifugal Pump is defined as the speed of a geometrically similar pump that would deliver one cubic meter of liquid per second against a head of one meter. It is a dimensionless parameter used to classify pump impellers based on their type and performance.

2. How Does the Calculator Work?

The calculator uses the Specific Speed formula:

\[ N_s = \frac{\omega \cdot \sqrt{Q}}{H_m^{3/4}} \]

Where:

\( N_s \) — Specific Speed of Centrifugal Pump (rad/s)
\( \omega \) — Angular Velocity (rad/s)
\( Q \) — Actual Discharge at Centrifugal Pump Outlet (m³/s)
\( H_m \) — Manometric Head of Centrifugal Pump (m)

Explanation: The formula relates the angular velocity, discharge, and manometric head to determine the specific speed, which characterizes the pump's performance and design.

3. Importance of Specific Speed Calculation

Details: Specific speed is crucial for pump selection, design optimization, and performance prediction. It helps in classifying pumps into radial, mixed-flow, and axial types based on their operating characteristics.

4. Using the Calculator

Tips: Enter angular velocity in rad/s, actual discharge in m³/s, and manometric head in meters. All values must be positive and valid.

5. Frequently Asked Questions (FAQ)

Q1: What is the range of specific speed for different pump types?
A: Radial flow pumps typically have specific speeds below 0.9, mixed-flow pumps between 0.9-1.6, and axial flow pumps above 1.6.

Q2: How does specific speed affect pump efficiency?
A: Pumps are designed to operate most efficiently at their specific design speed. Deviations from this speed can reduce efficiency.

Q3: Can specific speed be used for different fluids?
A: The specific speed concept is primarily for incompressible fluids. For compressible fluids, additional factors need consideration.

Q4: What are the limitations of specific speed?
A: Specific speed is most accurate for geometrically similar pumps operating under similar conditions and may not fully capture performance variations in different designs.

Q5: How is specific speed related to pump performance curves?
A: Specific speed helps predict the shape of pump performance curves, including head-capacity and efficiency characteristics.