1. What is a GPM Water Flow Calculator?

Definition: This calculator estimates water flow rate in gallons per minute (GPM) based on velocity and cross-sectional area.

Purpose: It helps engineers, plumbers, and irrigation specialists determine water flow rates in pipes and channels.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Flow rate (gallons per minute, GPM)
• \( V \) — Velocity (feet per second, ft/s)
• \( A \) — Cross-sectional area (square feet, ft²)
• \( 448.83 \) — Conversion factor (1 ft³/s = 448.83 GPM)

Explanation: The basic flow rate in ft³/s is calculated (V × A) and then converted to GPM.

3. Importance of Flow Rate Calculation

Details: Accurate flow rate calculations are essential for proper pipe sizing, pump selection, and system design in plumbing, irrigation, and industrial applications.

4. Using the Calculator

Tips: Enter the water velocity in ft/s and the cross-sectional area in ft². Both values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why multiply by 448.83?
A: This converts cubic feet per second (ft³/s) to gallons per minute (GPM), since 1 ft³/s = 448.83 GPM.

Q2: How do I measure velocity?
A: Use flow meters or calculate from head pressure (V = √(2gh), where g=32.2 ft/s², h=head in feet).

Q3: What's a typical pipe velocity?
A: Domestic water systems typically range 4-8 ft/s; irrigation systems 5-10 ft/s.

Q4: How do I calculate pipe area?
A: For circular pipes: A = π × (diameter/2)². For other shapes use appropriate area formulas.

Q5: Does this account for friction losses?
A: No, this calculates theoretical flow. Actual flow may be less due to pipe friction and fittings.