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GPM Flow Rate Formula:
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The GPM (Gallons Per Minute) flow rate formula calculates the volumetric flow rate of fluid through a pipe based on velocity and cross-sectional area. It's commonly used in plumbing, irrigation, and hydraulic systems design.
The calculator uses the GPM flow rate formula:
Where:
Explanation: The formula converts velocity and area measurements to gallons per minute, accounting for unit conversions between feet, inches, and gallons.
Details: Accurate flow rate calculation is essential for proper system design, ensuring adequate water supply, preventing pressure drops, and optimizing pump selection in various fluid systems.
Tips: Enter velocity in ft/s and cross-sectional area in in². Both values must be positive numbers. For circular pipes, area can be calculated as π × (diameter/2)².
Q1: Why is the conversion factor 0.408?
A: The factor 0.408 converts from ft/s × in² to gal/min, accounting for 1 ft³ = 7.48052 gallons and 1 ft² = 144 in².
Q2: What are typical flow rates for residential plumbing?
A: Typical flow rates range from 2-8 GPM for showers, 1.5-3 GPM for faucets, and 3-7 GPM for toilet flush valves.
Q3: How does pipe diameter affect flow rate?
A: Flow rate increases with the square of the diameter (for the same velocity), so doubling pipe diameter quadruples the flow capacity.
Q4: When is this formula not accurate?
A: This formula assumes steady, laminar flow and may be less accurate for highly viscous fluids, turbulent flow, or non-circular pipes.
Q5: Can this be used for other fluids besides water?
A: Yes, but the conversion factor (0.408) is specific to water. For other fluids, additional density or viscosity corrections may be needed.