Calculate GPM from PSI and Pipe Size

Flow Rate Formulas:

\[ V = \sqrt{\frac{2 \times (P_1 - P_2) \times 144}{\rho}} \] \[ Q = V \times A \times 448.83 \]

Upstream Pressure (P₁):

psi

Downstream Pressure (P₂):

psi

Fluid Density (ρ):

lb/ft³

Pipe Diameter:

inches

Velocity (V): ft/s

Flow Rate (Q): GPM

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1. What is GPM from PSI and Pipe Size Calculator?

Definition: This calculator estimates the flow rate (in gallons per minute) through a pipe based on pressure difference and pipe diameter.

Purpose: It helps engineers, plumbers, and fluid system designers determine flow rates in piping systems.

2. How Does the Calculator Work?

The calculator uses two main formulas:

\[ V = \sqrt{\frac{2 \times (P_1 - P_2) \times 144}{\rho}} \] \[ Q = V \times A \times 448.83 \]

Where:

\( V \) — Velocity (feet per second)
\( P_1 \) — Upstream pressure (psi)
\( P_2 \) — Downstream pressure (psi)
\( \rho \) — Fluid density (pounds per cubic foot)
\( Q \) — Flow rate (gallons per minute)
\( A \) — Cross-sectional area of pipe (square feet)

Explanation: The pressure difference is converted to velocity, which is then multiplied by pipe area and a conversion factor to get flow rate.

3. Importance of Flow Rate Calculation

Details: Accurate flow rate estimation ensures proper system design, adequate pressure maintenance, and efficient operation of fluid systems.

4. Using the Calculator

Tips: Enter the pressure values (P₁ must be greater than P₂), fluid density (default 62.4 lb/ft³ for water), and pipe diameter in inches.

5. Frequently Asked Questions (FAQ)

Q1: Why is the 144 factor in the velocity formula?
A: It converts psi (lb/in²) to lb/ft² (1 ft² = 144 in²).

Q2: What's the 448.83 conversion factor for?
A: It converts ft³/s to GPM (1 ft³/s = 448.83 GPM).

Q3: What density should I use for other fluids?
A: Use 49.2 lb/ft³ for gasoline, 78.6 lb/ft³ for seawater, or look up specific values for your fluid.

Q4: Does this account for friction losses?
A: No, this is an ideal calculation. For real-world applications, consider additional friction factors.

Q5: What if my pipe isn't circular?
A: Use the equivalent circular diameter or calculate the actual cross-sectional area of your pipe shape.