Compressor CFM Calculation Formula

Compressor CFM Formula:

\[ CFM = \frac{Displacement \times RPM}{1728} \]

CFM (Free Air Delivery):

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1. What is Compressor CFM Calculation?

The Compressor CFM (Cubic Feet per Minute) calculation determines the free air delivery capacity of an air compressor. It represents the volume of air the compressor can deliver at a specific pressure and is crucial for selecting the right compressor for various applications.

2. How Does the Calculator Work?

The calculator uses the compressor CFM formula:

\[ CFM = \frac{Displacement \times RPM}{1728} \]

Where:

\( CFM \) — Cubic Feet per Minute (free air delivery)
\( Displacement \) — Compressor displacement in cubic inches per revolution
\( RPM \) — Revolutions per minute of the compressor
\( 1728 \) — Conversion factor (cubic inches per cubic foot)

Explanation: This formula calculates the theoretical maximum air delivery of a compressor based on its physical displacement and operating speed.

3. Importance of CFM Calculation

Details: Accurate CFM calculation is essential for matching compressor capacity to air tool requirements, ensuring efficient operation, preventing compressor overload, and maintaining proper system pressure.

4. Using the Calculator

Tips: Enter displacement in cubic inches per revolution and RPM values. Both values must be positive numbers. The result represents free air delivery at standard atmospheric conditions.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between CFM and SCFM?
A: CFM measures actual cubic feet per minute, while SCFM (Standard Cubic Feet per Minute) measures air flow at standard conditions (68°F, 36% relative humidity, 14.7 psia).

Q2: Why is 1728 used in the formula?
A: 1728 represents the number of cubic inches in one cubic foot (12 inches × 12 inches × 12 inches = 1728 in³/ft³).

Q3: What is typical CFM range for compressors?
A: Small workshop compressors: 2-10 CFM, Industrial compressors: 10-100+ CFM, Large industrial systems: 100-5000+ CFM.

Q4: How does pressure affect CFM?
A: As pressure increases, actual CFM decreases due to compression. This formula calculates displacement CFM, not accounting for pressure losses.

Q5: What factors affect actual CFM delivery?
A: Altitude, temperature, humidity, compressor efficiency, piping losses, and air leaks can all affect actual CFM delivery compared to calculated values.