GPM from Pipe Size and Pressure

Flow Rate Formula:

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

Inlet Pressure (P₁):

psi

Outlet Pressure (P₂):

psi

Fluid Density (ρ):

lb/ft³

Pipe Diameter:

inches

Velocity (V): ft/s

Flow Rate (Q): GPM

Unit Converter ▲

Unit Converter ▼

From:	To:

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

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

Purpose: It helps engineers, plumbers, and fluid system designers determine flow rates for various applications.

2. How Does the Calculator Work?

The calculator uses these formulas:

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

Where:

\( V \) — Fluid velocity (ft/s)
\( P_1 \) — Inlet pressure (psi)
\( P_2 \) — Outlet pressure (psi)
\( \rho \) — Fluid density (lb/ft³)
\( Q \) — Flow rate (GPM)
\( A \) — Cross-sectional area of pipe (ft²)

Explanation: The pressure difference drives the flow, and the pipe diameter determines how much fluid can pass through.

3. Importance of Flow Rate Calculation

Details: Proper flow rate estimation ensures adequate system performance, prevents pipe damage, and helps in pump selection.

4. Using the Calculator

Tips: Enter the pressure values (psi), fluid density (default 62.4 lb/ft³ for water), and pipe diameter (inches). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's the typical density for water?
A: Water at 60°F has a density of 62.4 lb/ft³. For other fluids, check material specifications.

Q2: How does pipe diameter affect flow rate?
A: Flow rate increases with the square of the pipe diameter - doubling diameter quadruples flow capacity.

Q3: What if my outlet pressure is zero?
A: This represents flow into atmosphere. Just enter 0 for P₂.

Q4: Does this account for friction losses?
A: No, this is theoretical maximum. Actual flow will be less due to pipe friction and fittings.

Q5: What's the conversion factor 448.83 for?
A: It converts ft³/s to GPM (1 ft³/s = 448.83 GPM).