Calculate Pump Horsepower From Flow And Head

Hydraulic Horsepower Formula:

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

Flow Rate (Q):

gpm

Head (H):

Specific Gravity (SG):

Efficiency (η):

Hydraulic Horsepower (HP):

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1. What Is Hydraulic Horsepower?

Hydraulic horsepower represents the power required to move a fluid through a system, accounting for flow rate, head pressure, fluid density, and pump efficiency. It's essential for proper pump selection and system design.

2. How Does The Calculator Work?

The calculator uses the hydraulic horsepower formula:

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

Where:

\( Q \) — Flow rate in gallons per minute (gpm)
\( H \) — Head in feet (ft)
\( SG \) — Specific gravity of the fluid (dimensionless)
\( \eta \) — Pump efficiency as a percentage (%)
3960 — Conversion constant for units

Explanation: This formula calculates the actual power required at the pump shaft, accounting for the pump's efficiency in converting mechanical energy to hydraulic energy.

3. Importance Of Pump Horsepower Calculation

Details: Accurate horsepower calculation is crucial for selecting properly sized pumps, motors, and drives, ensuring energy efficiency, preventing overload conditions, and optimizing system performance.

4. Using The Calculator

Tips: Enter flow rate in gpm, head in feet, specific gravity (1.0 for water), and pump efficiency as a percentage. All values must be positive numbers with efficiency between 0-100%.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between hydraulic HP and brake HP?
A: Hydraulic HP is the power imparted to the fluid, while brake HP is the power required at the pump shaft (includes efficiency losses).

Q2: Why is specific gravity important?
A: Specific gravity affects the fluid density - heavier fluids require more power to pump at the same flow rate and head.

Q3: What are typical pump efficiencies?
A: Centrifugal pumps typically range from 50-85% efficiency, with higher efficiencies for larger, well-designed pumps.

Q4: How does head affect horsepower requirements?
A: Horsepower increases linearly with both flow rate and head - doubling either parameter doubles the horsepower requirement.

Q5: When should motor service factor be considered?
A: Always select a motor with adequate service factor (typically 1.15-1.25) to handle temporary overload conditions and ensure long motor life.