Power Formula for Pump

Pump Power Formula:

\[ HP = \frac{Q \times H \times \rho}{3960 \times \eta} \]

Flow Rate (Q):

GPM

Head (H):

Density (ρ):

lb/gal

Efficiency (η):

Pump Power (HP):

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1. What is the Pump Power Formula?

Definition: This calculator determines the horsepower required by a pump based on flow rate, head, fluid density, and pump efficiency.

Purpose: It helps engineers and technicians properly size pumps for various fluid transfer applications.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ HP = \frac{Q \times H \times \rho}{3960 \times \eta} \]

Where:

\( HP \) — Horsepower required
\( Q \) — Flow rate (gallons per minute)
\( H \) — Total head (feet)
\( \rho \) — Fluid density (pounds per gallon)
\( \eta \) — Pump efficiency (decimal, 0-1)

Explanation: The formula calculates the theoretical power needed to move a fluid at a given rate against a specific head, adjusted for pump efficiency.

3. Importance of Pump Power Calculation

Details: Proper pump sizing ensures efficient operation, prevents motor overload, and reduces energy costs.

4. Using the Calculator

Tips: Enter the flow rate in GPM, head in feet, fluid density (default 8.34 lb/gal for water), and pump efficiency (default 0.85). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is the 3960 constant in the formula?
A: It's a conversion factor that combines unit conversions to give the result directly in horsepower.

Q2: What's a typical pump efficiency value?
A: Most centrifugal pumps operate between 70-90% efficiency (0.7-0.9).

Q3: How do I determine total head (H)?
A: Total head includes static head, friction losses, and pressure differences in the system.

Q4: What density should I use for other fluids?
A: For other fluids, use their specific weight divided by 7.48 (gallons per cubic foot).

Q5: Should I add a safety factor?
A: Yes, it's common to add 10-20% to the calculated horsepower for safety margins.