Air Compressors

CFM vs SCFM for Air Compressor | Buying Guide 2020

With each passing day, technology is entering into our lives at a very fast pace. With the advancing technology, most of our mechanical work is replaced by electrical systems.

Nowadays there are multiple tools that have found their substitute in electrical setups. However, there is one system that is still under high demand i.e. air compressor powered-technique.

Today markets are piled up with a variety of air compressors. Each air compressor has it’s distinct features and specific applications. They are available in different sizes, especially tank size and piston positioning.

To better understand the function of an air compressor, you should be aware of various ratings that are vital to any air compressor. An air compressor can be rated in CFM, SCFM, PSI, and duty cycle at a specified pressure.

It is very important to have complete expertise and understanding about units an air compressor is measured in.

Units used in Air Compressor Ratings

Mainly there are two basic units we used to measure the pressure of airflow SCFM, and CFM.

Before putting your money into an air compressor, you should learn and understand some basic differences between CFM and SCFM.

Cubic Feet per Minute (CFM)

In the USA, the volume of airflow delivered by a compressor to a device is measured in units of cubic feet per minute. It represents the air providing capability of air compressor.

CFM is used in device systems where you are unaware of the temperature and pressure of air.

How much CFM is Required

The greater the value of CFM, the more an air compressor has a tendency to operate a heavy machine.

This means that by looking at the value of CFM, you can easily determine how much power will be generated towards your tool you want to operate with an air compressor.

If you know the nature of your task and the power your machine needs, then selecting CFM is not rocket science.

Relation of Pounds per Square Inch (PSI) and CFM

CFM of an air compressor depends upon pounds per square inch.

It is advisable to always invest in an air compressor that has a higher than required value of CFM so that it can be utilized later with heavy machines as well.

If an air compressor is valued for certain CFM at 100 PSI, it may not guarantee an increased CFM at 90 PSI. Some air can be dissipated by the piston with each stroke while remaining air in reducing friction.

Why CFM is just Used as a Guideline

You should use CFM values only for guidance and recommendations.

CFM is usually looked like an old-style of ratings as it does not give you an exact value of power that you are expecting.

Some of the power delivered by air compressors may be lost in overcoming friction and heat causing a noticeable decrease in airflow.

The actual volumetric airflow coming out from a compressor is measured with another unit known as ACFM or actual CFM.

Standard Cubic Feet per Minute (SCFM)

It is the most advanced scientific way of rating an air compressor.

It is also the amount of air compressor can provide to a machine. It is the measurement of air at standard conditions such as temperature, pressure, and level of humidity.

SCFM is related to unit time i.e, how much time air will take to emerge from an air compressor.

Conversion of SCFM to the CFM scale will require standard values of temperature, pressure, and humidity, as they are a, must component of SCFM.

Major Difference Between SCFM and CFM

However, there is a difference between SCFM and CFM.

SCFM is calculated in a known environment with controlled values of temperature and pressure.

CFM, on the other hand, is measured in an environment where values of temperature and pressure are unknown.

SCFM is a realistic way of calculation. CFM is an ideal way of calculation.

SCFM takes into consideration all influencing factors such as humidity, temperature, pressure ( both atmospheric and contextual). CFM does not require any of these factors for its measurement.

Campbell used the word CFM for an air compressor and SCFM while talking about any air device.

Evaluation of SCFM and CFM

CFM values are usually less as compared to the SCFM scale of measurement.

It is because of the manufacturer’s design CFM of an air compressor at a value of air pressure approximately 90PSI ( that’s why lesser air volume). Ultimately SFCM values are greater.

SCFM is calculated by noticing the standard values of temperature( 20°C), pressure ( 14.7 PSI), and almost 36% humidity.

How to Decide about an Air Compressor to Buy

An air compressor is marked with certain values of CFM and SCFM.

SCFM marks the value of air emerging from a compressor at standard conditions of temperature, atmospheric pressure, and humidity.

CFM does not follow any standard conditions for its measurement.

The perfect way of selecting an air compressor is to decide the demand of your instrument and multiply it by 1.5.

For example, you are going to select an air tool that requires 5.9 SCFM, you are actually buying an air compressor with a capability of 8.85 CFM ( multiply 5.9 by 1.5).

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