How To Calculate Compressor Capacity

Compressor Capacity Formula:

\[ \text{Capacity (CFM)} = \frac{\text{Displacement} \times \text{RPM} \times \text{Volumetric Efficiency}}{1728} \]

Capacity (CFM):

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1. What Is Compressor Capacity?

Compressor capacity, measured in cubic feet per minute (CFM), represents the volume of air that a compressor can deliver at a specific pressure. It is a critical parameter for determining if a compressor can meet the air demand of your tools and equipment.

2. How Does The Calculator Work?

The calculator uses the compressor capacity formula:

\[ \text{Capacity (CFM)} = \frac{\text{Displacement} \times \text{RPM} \times \text{Volumetric Efficiency}}{1728} \]

Where:

\( \text{Displacement} \) — Compressor displacement in cubic inches (in³)
\( \text{RPM} \) — Rotational speed in revolutions per minute
\( \text{Volumetric Efficiency} \) — Efficiency percentage of the compressor
\( 1728 \) — Conversion factor (12³) to convert cubic inches to cubic feet

Explanation: The formula calculates the actual air delivery capacity by accounting for the compressor's physical displacement, operating speed, and efficiency losses.

3. Importance Of Compressor Capacity Calculation

Details: Accurate capacity calculation is essential for proper compressor selection, ensuring adequate air supply for pneumatic tools, optimizing energy consumption, and preventing system overload.

4. Using The Calculator

Tips: Enter displacement in cubic inches, RPM in revolutions per minute, and volumetric efficiency as a percentage. All values must be positive numbers with efficiency between 0-100%.

5. Frequently Asked Questions (FAQ)

Q1: What is volumetric efficiency?
A: Volumetric efficiency represents how effectively the compressor pumps air compared to its theoretical maximum. Typical values range from 70-90% for reciprocating compressors.

Q2: Why divide by 1728?
A: 1728 is the number of cubic inches in a cubic foot (12 × 12 × 12), converting the result from cubic inches per minute to cubic feet per minute.

Q3: What is typical compressor displacement?
A: Displacement varies by compressor size. Small portable compressors may have 10-30 in³ displacement, while industrial units can exceed 200 in³.

Q4: How does RPM affect capacity?
A: Higher RPM increases capacity proportionally, but may reduce efficiency and compressor lifespan due to increased wear and heat generation.

Q5: What factors affect volumetric efficiency?
A: Valve design, compression ratio, clearance volume, operating temperature, and mechanical condition all impact volumetric efficiency.