Pipe Size Flow Calculator

Pipe Diameter Formula:

\[ D = \sqrt{\frac{4 \times Q}{V \times \pi \times 7.481}} \]

Pipe Diameter (ft):

Pipe Diameter (in):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is a Pipe Size Flow Calculator?

Definition: This calculator determines the required pipe diameter based on flow rate and fluid velocity.

Purpose: It helps engineers, plumbers, and designers select the appropriate pipe size for fluid systems.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ D = \sqrt{\frac{4 \times Q}{V \times \pi \times 7.481}} \]

Where:

\( D \) — Pipe diameter (feet)
\( Q \) — Flow rate (gallons per minute)
\( V \) — Fluid velocity (feet per second)
\( \pi \) — Pi (approximately 3.1416)
7.481 — Conversion factor (gallons to cubic feet)

Explanation: The formula calculates the pipe diameter needed to maintain a specific flow velocity for a given flow rate.

3. Importance of Proper Pipe Sizing

Details: Correct pipe sizing ensures efficient flow, prevents excessive pressure drops, and minimizes energy costs in pumping systems.

4. Using the Calculator

Tips: Enter the flow rate in GPM and desired velocity in ft/s (default 5 ft/s for water). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical velocity for water in pipes?
A: For water, 3-5 ft/s is common for supply lines, 5-10 ft/s for drainage.

Q2: Why is velocity important in pipe sizing?
A: Higher velocities increase friction losses and noise; lower velocities may allow sediment buildup.

Q3: Does this work for gases or other fluids?
A: The formula works for any fluid, but velocity limits vary by fluid type and application.

Q4: How do I convert the result to nominal pipe size?
A: Round up to the nearest standard pipe size available in your region.

Q5: What's the 7.481 conversion factor for?
A: It converts gallons to cubic feet (1 cubic foot = 7.481 gallons).