Pump Horsepower Calculator

Pump Horsepower Formula:

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

Flow Rate (Q):

GPM

Head (H):

Specific Gravity (SG):

(1 for water)

Efficiency (η):

decimal (0-1)

Pump Horsepower (HP):

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1. What is Pump Horsepower?

Pump horsepower (HP) is the power required to move a fluid at a specified flow rate against a specified head, accounting for the fluid's specific gravity and the pump's efficiency. It's a crucial parameter in pump selection and system design.

2. How Does the Calculator Work?

The calculator uses the pump horsepower formula:

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

Where:

\( Q \) — Flow rate (gallons per minute, GPM)
\( H \) — Total dynamic head (feet, ft)
\( SG \) — Specific gravity (dimensionless, 1 for water)
\( \eta \) — Pump efficiency (decimal, 0-1)
3960 — Conversion factor (ft-lb/min per HP)

Explanation: The formula calculates the power needed to move a fluid based on the flow rate, the pressure head it must overcome, the fluid's density relative to water, and the pump's efficiency.

3. Importance of Pump Horsepower Calculation

Details: Proper horsepower calculation ensures correct pump selection, prevents underpowered or oversized pumps, and helps in energy efficiency planning. It's essential for system design and operational cost estimation.

4. Using the Calculator

Tips: Enter flow rate in GPM, head in feet, specific gravity (1 for water), and pump efficiency as a decimal (e.g., 0.85 for 85%). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is specific gravity?
A: Specific gravity is the ratio of the fluid's density to water's density at standard conditions. Water has SG=1, while heavier fluids have SG>1.

Q2: What is a typical pump efficiency?
A: Centrifugal pumps typically range from 40-85% efficiency, with larger pumps generally more efficient. Positive displacement pumps can reach 90% efficiency.

Q3: How do I account for motor efficiency?
A: Motor efficiency is separate from pump efficiency. To get brake horsepower (BHP), divide pump HP by motor efficiency.

Q4: What's the difference between water horsepower and brake horsepower?
A: Water HP is the theoretical power needed to move the fluid. Brake HP includes pump inefficiencies and is what the motor must deliver.

Q5: How does viscosity affect horsepower?
A: Higher viscosity fluids require more power to pump. For viscous fluids, corrections to the standard formula may be needed.