Pump Power Calculation Formula

Pump Power Equation:

\[ P = \frac{\rho \times g \times Q \times H}{\eta} \]

Density (ρ):

kg/m³

Flow Rate (Q):

m³/s

Head (H):

meters

Efficiency (η):

(0-1)

Pump Power (P):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is the Pump Power Formula?

The pump power formula calculates the required power to move a fluid at a specified flow rate against a given head, accounting for the pump's efficiency. It's essential for selecting and sizing pumps in various engineering applications.

2. How Does the Calculator Work?

The calculator uses the pump power equation:

\[ P = \frac{\rho \times g \times Q \times H}{\eta} \]

Where:

\( P \) — Power (W)
\( \rho \) — Fluid density (kg/m³)
\( g \) — Gravitational acceleration (9.81 m/s²)
\( Q \) — Volumetric flow rate (m³/s)
\( H \) — Head (m)
\( \eta \) — Pump efficiency (0-1)

Explanation: The equation calculates the hydraulic power required to move the fluid, then divides by the pump efficiency to get the actual power requirement.

3. Importance of Pump Power Calculation

Details: Accurate pump power calculation ensures proper pump selection, prevents under/over-sizing, optimizes energy consumption, and helps design efficient fluid systems.

4. Using the Calculator

Tips:

For water, density is typically 1000 kg/m³
Flow rate must be in m³/s (convert from L/s by dividing by 1000)
Head is the total dynamic head (pressure + elevation + velocity heads)
Pump efficiency typically ranges from 0.5 to 0.9

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between hydraulic power and pump power?
A: Hydraulic power is the theoretical power needed to move the fluid, while pump power includes the efficiency factor (hydraulic power ÷ efficiency).

Q2: How do I convert the result to horsepower?
A: Multiply kW result by 1.341 to get horsepower (HP).

Q3: What's a typical pump efficiency value?
A: Centrifugal pumps typically range from 50-90% efficiency, with larger pumps generally being more efficient.

Q4: How does viscosity affect pump power?
A: Higher viscosity fluids require more power and may reduce pump efficiency. Specialized pumps are needed for high-viscosity fluids.

Q5: What if I need to account for system losses?
A: Include all pipe friction losses, fitting losses, and elevation changes in your total head (H) calculation.