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Pump Horsepower Formula:
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Pump horsepower (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 output.
The calculator uses the pump horsepower formula:
Where:
Explanation: This formula calculates the brake horsepower required by accounting for the hydraulic power needed to move the fluid and the pump's efficiency in converting mechanical energy to hydraulic energy.
Details: Accurate pump horsepower calculation is essential for proper pump selection, motor sizing, energy consumption estimation, and ensuring the pump operates within its designed capacity without overloading.
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%.
Q1: What is the difference between brake horsepower and water horsepower?
A: Water horsepower is the theoretical power required to move the fluid, while brake horsepower includes pump inefficiencies and represents the actual power input needed.
Q2: What is a typical pump efficiency range?
A: Pump efficiency typically ranges from 50% to 85%, depending on pump type, size, and operating conditions. Centrifugal pumps generally have higher efficiencies than positive displacement pumps.
Q3: Why is specific gravity important?
A: Specific gravity accounts for fluid density. Heavier fluids (SG > 1) require more power to pump, while lighter fluids (SG < 1) require less power compared to water.
Q4: How does head affect horsepower requirements?
A: Higher head (pressure) requires more horsepower. The relationship is linear - doubling the head doubles the horsepower requirement (assuming constant flow).
Q5: What motor size should I select?
A: Select a motor with horsepower rating 10-20% higher than the calculated brake horsepower to account for startup loads and provide a safety margin.