What is SCFM in Air Compressors – SCFM vs. CFM Explained (2024)

FAQs

What is SCFM in Air Compressors – SCFM vs. CFM Explained? ›

What's the Difference Between SCFM vs. CFM? SCFM and CFM are both essential values that indicate the airflow rate in a compressor. SCFM measures this value based on 'ideal' temperature and pressure conditions, while CFM measures the 'actual' air flow rate.

What's the difference between cfm and scfm? The most common air compressor ratings are cfm and scfm (standard cfm). So, what's the difference? As a measurement, cfm will be a smaller number than scfm, because cfm values are taken under pressure (typically 90 psi), so the air volume is small.

Smaller tools usually require between 0- to 5-SCFM, while larger tools can require 10- or more SCFM. To gauge the minimum compressor SCFM rating you need, examine the SCFM requirements of all the tools you intend to use. Multiply the highest tool rating by 1.5 to get the minimum compressor SCFM for your needs.

By calculating how much pressure you need for your application, you can verify you are working with the right air compressor by finding out its SCFM. An air compressor with 10 horsepower or more should generate around 3 or 4 cubic feet of air per minute at 90 PSI.

SCFM stands for standard cubic feet per minute, a measurement of airflow at a standard temperature, standard atmospheric pressure, and standard humidity. Because these conditions are carefully controlled, they produce a very precise reading of the volumetric flow rate of an air compressor.

Another parameter considered along with CFM is the amount of pressure that the air compressor can offer, which is measured in bar, kg/cm2 or PSI. For instance, small pneumatic tools usually need up to 5 CFM at 4.8-6.2 bar. Larger equipment, on the other hand, demand more than 10 CFM at 6.9-8.2 bar.

A higher CFM can support larger, heavy-duty applications, but it's important to know that higher CFM doesn't necessarily mean a better air compressor — it just means a bigger one.

When choosing an air compressor, consider the tools you want it to power. Determine which one requires the highest CFM at the highest PSI. Add 50 percent to the required CFM for a margin of safety, and look for a compressor that meets the requirement.

Air tools made for general use with portable air compressors typically require 0 to 5 cubic feet per minute (cfm) at 70 to 90 pounds per square inch (psi), whereas with larger tools connected to stationary systems, the requirements usually exceed 10 cfm at 100 to 120 psi.

How big of an air compressor do I need to run air tools? ›

As a guideline, most air compressors for powering tools fall in the 10 to 110 CFM range. Air compressors with lower CFM ratings work well for passenger tire inflation and small tools, such as chippers, grinders, and sanders.

The Occupational Safety and Health Administration (OSHA) standard 29 CFR 1910.242 (b) requires that the nozzle pressure of an air gun used for cleaning purposes remain below 30 pounds per square inch (psi) for all static conditions.

For an appropriate comparison between different compressors, it is better to use SCFM rating instead of the CFM rating, because in SCFM, all the measurements are calculated back to a set of standard conditions.

If you are using a gravity-feed or low-pressure spray gun, you will need an air compressor that can generate between 10 to 30 PSI. For HVLP (High Volume Low Pressure) spray guns, you will need an air compressor that generates between 15 to 50 PSI.

As you may remember, density = mass/volume. When the ideal gas law is rearranged, the air density can be seen to be proportional to pressure, and inversely proportional to temperature. Since the air density of an air flow stated at standard conditions (SCFM) is always the same, it is essentially a mass flow rate!

To get a feel for how much air (CFM) you will need, you can figure roughly 4-5 CFM per person in an automotive shop and 12-15 per person in a body shop. Once you determine the CFM you need, take that figure times 1.25 and use that total CFM to choose your compressor.

To convert actual cfm to standard cfm, multiply the actual cfm by FT and FA. To convert standard cfm to actual cfm, divide the standard cfm by FT and FA. Example: Convert 15,900 cfm of air at 95? and at 3,000-ft altitude to standard conditions.

Cubic Feet per Minute - or CFM - determines the amount of air that a fan can move through a room while operating at the highest speed. The larger the space, the higher the fan CFM must be in order to efficiently cool a room. CFM for fans is a critical measurement for determining the right fan for your space.