Air Compressor Flow Rate Calculator

CFM Formula:

\[ CFM = \frac{Tank\ Volume\ (gal) \times Pressure\ (psi)}{14.7 \times Time\ (min)} \]

CFM (Cubic Feet per Minute):

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1. What is CFM?

CFM (Cubic Feet per Minute) is a measurement of airflow volume that indicates how much air a compressor can deliver at a given pressure level. It's a crucial specification for determining compressor performance and capacity.

2. How Does the Calculator Work?

The calculator uses the CFM formula:

\[ CFM = \frac{Tank\ Volume\ (gal) \times Pressure\ (psi)}{14.7 \times Time\ (min)} \]

Where:

\( Tank\ Volume \) — Compressor tank capacity in gallons
\( Pressure \) — Operating pressure in psi
\( Time \) — Time to fill tank in minutes
\( 14.7 \) — Atmospheric pressure constant

Explanation: This formula calculates the actual airflow delivery of a compressor by measuring how quickly it can fill its tank to a specified pressure.

3. Importance of CFM Calculation

Details: Knowing your compressor's actual CFM is essential for selecting the right tools, ensuring adequate air supply for pneumatic equipment, and preventing compressor overload or underperformance.

4. Using the Calculator

Tips: Enter tank volume in gallons, pressure in psi, and fill time in minutes. All values must be positive numbers. For accurate results, measure the time it takes to fill the tank from empty to your desired operating pressure.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between CFM and SCFM?
A: CFM measures actual airflow at local conditions, while SCFM (Standard CFM) measures airflow at standard conditions (68°F, 0% humidity, sea level). SCFM is typically higher than CFM.

Q2: Why is 14.7 used in the formula?
A: 14.7 psi represents standard atmospheric pressure at sea level, which is used to convert between absolute pressure and gauge pressure in the calculation.

Q3: What is a good CFM for home use?
A: Most home workshops require 5-10 CFM for tools like nail guns, impact wrenches, and paint sprayers. Larger tools may require 15-20 CFM.

Q4: How does altitude affect CFM?
A: At higher altitudes, air is less dense, so compressors deliver less actual CFM. The formula assumes sea level conditions.

Q5: Can I use this for all compressor types?
A: This method works for reciprocating, rotary screw, and centrifugal compressors, but may be less accurate for very small or very large industrial systems.