Pump Horsepower Calculator

Pump Horsepower Formula:

\[ BHP = \frac{Q \times H \times SG}{3960 \times Efficiency} \]

Flow Rate (Q):

GPM

Head (H):

Specific Gravity (SG):

Efficiency:

decimal

Brake Horsepower (BHP):

Unit Converter ▲

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1. What is Pump Horsepower?

Pump horsepower (BHP - Brake Horsepower) is the actual power required by a pump to move fluid against a specific head and flow rate. It represents the mechanical power input needed at the pump shaft to achieve the desired hydraulic performance.

2. How Does the Calculator Work?

The calculator uses the pump horsepower formula:

\[ BHP = \frac{Q \times H \times SG}{3960 \times Efficiency} \]

Where:

\( BHP \) — Brake horsepower (hp)
\( Q \) — Flow rate (gallons per minute)
\( H \) — Total dynamic head (feet)
\( SG \) — Specific gravity of fluid (dimensionless)
\( Efficiency \) — Pump efficiency (decimal)
3960 — Conversion constant

Explanation: The formula calculates the mechanical power required to overcome hydraulic losses and move fluid through the system, accounting for pump efficiency.

3. Importance of Pump Horsepower Calculation

Details: Accurate horsepower calculation is essential for proper pump selection, motor sizing, energy consumption estimation, and system design optimization. Underestimating can lead to pump failure, while overestimating wastes energy and increases costs.

4. Using the Calculator

Tips: Enter flow rate in GPM, head in feet, 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 the difference between BHP and WHP?
A: BHP (Brake Horsepower) is power input to the pump shaft, while WHP (Water Horsepower) is the hydraulic power output. BHP = WHP / Efficiency.

Q2: What are typical pump efficiencies?
A: Centrifugal pumps typically range from 50-85% efficiency, with larger pumps generally being more efficient. Positive displacement pumps can reach 90%+ efficiency.

Q3: Why is specific gravity important?
A: Specific gravity affects the fluid density. Heavier fluids (SG > 1) require more power to pump, while lighter fluids (SG < 1) require less power.

Q4: How do I account for motor efficiency?
A: Motor horsepower = BHP / Motor Efficiency. Add 10-20% safety factor for motor selection.

Q5: What is the 3960 constant?
A: 3960 is the conversion factor that combines unit conversions for flow (GPM), head (ft), density (lb/ft³), and power (hp) in the imperial system.