Pump Motor kW Calculator for Sale

Pump Power Formula:

\[ kW = \frac{Flow\ Rate \times Head \times Specific\ Gravity}{367 \times Efficiency} \]

Flow Rate:

m³/h

Head:

meters

Specific Gravity:

(dimensionless)

Efficiency:

(decimal)

Required Motor Power:

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1. What is the Pump Power Formula?

The pump power formula calculates the required motor power in kilowatts (kW) based on flow rate, head, fluid properties, and pump efficiency. This is essential for selecting properly sized motors for pump applications.

2. How Does the Calculator Work?

The calculator uses the pump power formula:

\[ kW = \frac{Flow\ Rate \times Head \times Specific\ Gravity}{367 \times Efficiency} \]

Where:

\( Flow\ Rate \) — Volumetric flow rate in cubic meters per hour (m³/h)
\( Head \) — Total dynamic head in meters (m)
\( Specific\ Gravity \) — Ratio of fluid density to water density (dimensionless)
\( Efficiency \) — Pump efficiency as a decimal (typically 0.7-0.9)
367 — Conversion factor combining gravity acceleration and unit conversions

Explanation: The formula accounts for the hydraulic power needed to move the fluid against the system head, adjusted for fluid density and pump efficiency.

3. Importance of Proper Motor Sizing

Details: Correct motor sizing ensures efficient operation, prevents overload conditions, and reduces energy costs. Oversized motors waste energy while undersized motors may fail prematurely.

4. Using the Calculator

Tips: Enter flow rate in m³/h, head in meters, specific gravity (1.0 for water), and pump efficiency as a decimal (e.g., 0.85 for 85% efficiency). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical pump efficiency value?
A: Centrifugal pumps typically range from 70-90% efficiency, with higher efficiency in larger, well-designed pumps.

Q2: How do I account for motor efficiency?
A: This calculation gives hydraulic power. Divide by motor efficiency (typically 0.9-0.95) to get electrical input power.

Q3: What safety factor should I add?
A: Common practice adds 10-20% to the calculated power for safety margin and future capacity.

Q4: How does viscosity affect the calculation?
A: High viscosity fluids may require additional power. The calculator assumes Newtonian fluids with viscosity similar to water.

Q5: Can I use this for positive displacement pumps?
A: This formula is primarily for centrifugal pumps. Positive displacement pumps require different calculations considering pressure rather than head.