Formula for Calculating Brake Horsepower

Brake Horsepower Formula:

\[ BHP = \frac{GPM \times Head \times SG}{3960 \times Eff} \]

GPM (Gallons Per Minute):

GPM

Head:

feet

Specific Gravity (SG):

Efficiency (Eff):

decimal

Brake Horsepower (BHP):

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1. What is Brake Horsepower?

Brake Horsepower (BHP) is the actual horsepower delivered to the pump shaft, representing the power required to drive the pump. It accounts for the pump's efficiency and is a crucial parameter in pump selection and system design.

2. How Does the Calculator Work?

The calculator uses the Brake Horsepower formula:

\[ BHP = \frac{GPM \times Head \times SG}{3960 \times Eff} \]

Where:

\( BHP \) — Brake Horsepower (HP)
\( GPM \) — Gallons Per Minute (flow rate)
\( Head \) — Total Dynamic Head (feet)
\( SG \) — Specific Gravity of the fluid
\( Eff \) — Pump Efficiency (decimal)
\( 3960 \) — Conversion constant

Explanation: The formula calculates the actual power required at the pump shaft by considering flow rate, pressure head, fluid density, and pump efficiency.

3. Importance of BHP Calculation

Details: Accurate BHP calculation is essential for proper pump selection, motor sizing, energy consumption estimation, and ensuring the pump operates within its designed capacity to prevent overload and equipment failure.

4. Using the Calculator

Tips: Enter GPM in gallons per minute, Head in feet, Specific Gravity as a dimensionless number (1.0 for water), and 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: Brake Horsepower (BHP) is power at the pump shaft, while Water Horsepower (WHP) is the hydraulic power delivered to the fluid. BHP = WHP / Efficiency.

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

Q3: What is a typical pump efficiency range?
A: Pump efficiency typically ranges from 50% to 85%, depending on pump type, size, and operating conditions.

Q4: How does head affect BHP?
A: Higher head requires more power. BHP is directly proportional to head - doubling the head doubles the BHP requirement.

Q5: What is the significance of the 3960 constant?
A: 3960 is a conversion factor that converts (GPM × feet × lb/gal) to horsepower, where 1 horsepower = 33,000 ft-lb/min.