Pump Motor Power Calculator

Pump Power Formula:

\[ kW = \frac{Flow\ (m³/h) \times Head\ (m) \times SG}{3600 \times Efficiency} \]

Flow Rate:

m³/h

Head:

Specific Gravity (SG):

unitless

Efficiency:

decimal

Motor Power:

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1. What is Pump Motor Power?

Pump motor power is the amount of electrical power required to drive a pump, calculated based on hydraulic power requirements and pump efficiency. It determines the size of motor needed for proper pump operation.

2. How Does the Calculator Work?

The calculator uses the pump power formula:

\[ kW = \frac{Flow\ (m³/h) \times Head\ (m) \times SG}{3600 \times Efficiency} \]

Where:

\( Flow \) — Volumetric flow rate in cubic meters per hour
\( Head \) — Total dynamic head in meters
\( SG \) — Specific gravity of the fluid (unitless)
\( Efficiency \) — Pump efficiency as a decimal (0.0 to 1.0)
\( 3600 \) — Conversion factor from hours to seconds

Explanation: The formula calculates the hydraulic power required and divides by pump efficiency to determine the actual motor power needed.

3. Importance of Pump Power Calculation

Details: Accurate pump motor power calculation is essential for proper pump selection, energy efficiency, preventing motor overload, and ensuring reliable system operation.

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., 0.75 for 75% efficiency). All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is specific gravity (SG)?
A: Specific gravity is the ratio of fluid density to water density at 4°C. Water has SG = 1.0, while other fluids vary (e.g., oil ~0.8, brine ~1.2).

Q2: How do I determine pump efficiency?
A: Pump efficiency varies by type and size. Typical values range from 0.5 to 0.85. Consult pump performance curves or manufacturer specifications.

Q3: Why is there a 3600 in the formula?
A: This converts flow from m³/h to m³/s, as power calculations require consistent SI units (1 hour = 3600 seconds).

Q4: Should I add a safety factor?
A: Yes, typically add 10-20% safety margin to the calculated power for motor selection to account for variations and future requirements.

Q5: Can this be used for all pump types?
A: This formula works for centrifugal and positive displacement pumps, though efficiency values and additional factors may vary by pump type.