Compressed Air CFM Calculator

Compressed Air Flow Formula:

\[ Q_{cfm} = V \times A \times 60 \]

Air Flow (Q_cfm): ft³/min

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1. What is a Compressed Air CFM Calculator?

Definition: This calculator estimates the volumetric flow rate of compressed air in cubic feet per minute (CFM) based on air velocity and pipe cross-sectional area.

Purpose: It helps engineers, HVAC technicians, and industrial professionals properly size compressed air systems and components.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ Q_{cfm} = V \times A \times 60 \]

Where:

\( Q_{cfm} \) — Air flow rate (cubic feet per minute)
\( V \) — Air velocity (feet per second)
\( A \) — Cross-sectional area (square feet)
60 — Conversion factor (seconds to minutes)

Explanation: The formula converts velocity in a pipe to volumetric flow rate by accounting for the pipe size and converting time units.

3. Importance of CFM Calculation

Details: Accurate CFM calculations ensure proper system performance, prevent pressure drops, and help select correctly sized compressors and piping.

4. Using the Calculator

Tips: Enter the air velocity in ft/s and the cross-sectional area in ft². For circular pipes, area = π × (diameter/2)².

5. Frequently Asked Questions (FAQ)

Q1: What's a typical air velocity for compressed air systems?
A: Most systems are designed for 20-30 ft/s in main lines and 30-40 ft/s in branch lines.

Q2: How do I calculate area for a round pipe?
A: Use A = π × r² where r is the radius in feet (diameter/2).

Q3: Why multiply by 60 in the formula?
A: This converts seconds to minutes since CFM is per minute while velocity is per second.

Q4: What affects compressed air velocity?
A: Pressure, pipe size, temperature, and flow restrictions all impact velocity.

Q5: How does CFM relate to compressor sizing?
A: Your compressor must supply at least the total CFM required by all tools plus a safety margin (typically 25-30%).