1. What is the Pump Flow Rate Formula?

Definition: This calculator determines the flow rate of a pump in gallons per minute (GPM) based on horsepower, efficiency, and total head.

Purpose: It helps engineers and technicians evaluate pump performance and select appropriate pumps for fluid systems.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Flow rate (gallons per minute)
• \( HP \) — Pump horsepower
• \( \eta \) — Pump efficiency (dimensionless, 0-1)
• \( H \) — Total head (feet)
• \( 8.34 \) — Weight of water (lb/gal)
• \( 3960 \) — Conversion constant (ft-lb/min per HP)

Explanation: The formula relates the power input to the pump with the hydraulic work done (flow against head).

3. Importance of Pump Flow Rate Calculation

Details: Accurate flow rate calculation ensures proper system design, energy efficiency, and prevents pump overload or underutilization.

4. Using the Calculator

Tips: Enter the pump horsepower, efficiency (default 0.85 for 85%), and total head in feet. All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is pump efficiency?
A: Pump efficiency (η) is the ratio of hydraulic power delivered to the fluid to the mechanical power input (0-1 scale, typically 0.7-0.9).

Q2: How is total head measured?
A: Total head is the height a pump can move fluid against gravity, including friction losses (measured in feet).

Q3: Why 3960 in the formula?
A: 3960 converts horsepower (550 ft-lb/sec) to ft-lb/min (550 × 60 = 33,000), then divides by 8.33 lb/gal ≈ 3960.

Q4: Can this be used for other fluids?
A: Yes, but replace 8.34 with the specific weight of your fluid (lb/gal).

Q5: What's a typical efficiency value?
A: Centrifugal pumps typically range 70-90% (0.7-0.9), while positive displacement pumps can exceed 90%.