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 equation:

Where:

• \( Flow \) — Flow rate in gallons per minute (gpm)
• \( Head \) — Total dynamic head in feet (ft)
• \( SG \) — Specific gravity of the fluid (dimensionless)
• \( Efficiency \) — Pump efficiency as a decimal (0.0 to 1.0)
• 3960 — Conversion factor to convert to horsepower

Explanation: The equation calculates the theoretical power required to move the fluid, then divides by the pump's efficiency to get actual required horsepower.

3. Importance of Pump HP Calculation

Details: Accurate horsepower calculation is essential for proper pump selection, motor sizing, and ensuring the system operates efficiently without overloading the motor.

4. Using the Calculator

Tips: Enter flow rate in gpm, head in feet, specific gravity (1.0 for water), and pump efficiency (typically 0.7-0.9 for centrifugal pumps). 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=1.0.

Q2: How do I estimate pump efficiency?
A: Centrifugal pumps typically have 70-90% efficiency. Check manufacturer curves for specific pumps.

Q3: What is the 3960 constant?
A: It's the conversion factor: (33000 ft-lb/min per HP) ÷ (8.33 lb/gal × 60 min/hr) ≈ 3960.

Q4: Should I add a safety factor?
A: Yes, typically add 10-25% to the calculated HP for motor selection to account for variations.

Q5: Can this be used for viscous fluids?
A: This is for Newtonian fluids. For viscous fluids, correction factors are needed.