Air compressors are essential tools that help convert unfiltered air into compressed air so you can get the job done. However, these machines offer a unique set of features and have different applications, and choosing the right compressor for your application is not always a straightforward task. It can especially get confusing to keep track of various ratings and specifications and understanding what they all mean. Although manufacturers are good at playing the rating game to advertise their products, having a good understanding of these specifications will help you choose the right compressor for your needs.
Air compressor specifications: The basics you need to know
CFM/SCFM (Cubic feet per minute)
CFM stands for cubic feet per minute, and it is a crucial consideration when comparing air compressors. Compressor CFM represents the volume of air the compressor can produce/deliver to air tools at a given pressure level. Various air tools require different output capacity to do their jobs properly, and this an important consideration, especially if you intend to run multiple devices simultaneously.
As a general rule of thumb, air compressors with higher CFM ratings provide more air and vice versa. So, for larger applications and tools that require a continuous supply of air, you will need a compressor with higher CFM. On the other hand, smaller tools such as a nail gun only require short bursts of air occasionally, so a lower CFM will be sufficient.
For best results, always go for an air compressor with a CFM output that is slightly higher than the requirement of the tool you anticipate to use. For power-hungry machines such as plasma cutters, you may need to purchase a compressor with an output of 1.5 times their CFM rating.
Typically, it is crucial to consider both the operating pressure and flow rate (CFM) to understand the suitability of your compressor. Also, when calculating your CFM requirements, you’ll need to consider whether you intend to use your machine continuously or occasionally.
Other than the CFM rating, you are likely to come across the SFCM (standard cubic feet per minute) rating. This is also a unit for measuring the volume of air an air compressor can deliver, but this is done in a controlled environment. While CFM is measured in variable conditions, SCFM is measured in standard conditions where temperature, pressure, and relative humidity are predetermined.
PSI (Pounds per square inch
As noted earlier, the work of a compressor is to pressurize intake air for different applications and processes. This is measured in pounds per square inch or PSI, which is basically the amount of force/ pressure the air compressor can deliver. While CFM indicates volume, PSI measures pressure produced by an air compressor to power various air tools.
Most air tools are rated at 40 or 90 PSI, but some heavy-duty tools will demand more. It is recommended to choose an air compressor that offers more pressure but always follow the PSI rating. If you don’t get enough air pressure, your device will not operate correctly while on the other hand, too much pressure can damage your tools.
The HP or horsepower rating is not as important as the flowrate or pressure rating, but it tells you how powerful the motor is. The motor’s work is to drive the cylinders to compress air, and it is rated in HP. Generally, compressors have a HP rating of between 1.5-6.5 HP though larger, heavy-duty compressors can go up to 15 HP. However, it is important to emphasize that you should not use horsepower alone to determine how powerful an air compressor is.
A powerful motor may not be ideal if the compressor does not deliver enough CFM or PSI. High rated compressors can perform efficiently with less HP as long as the compressor provides sufficient airflow at the correct pressure level. Working with less HP allows you to save more energy while giving you more returns throughout the operation.
The dB or simply decibel is the measurement of the loudness of the sound produced by an air compressor. Although this rating does not affect its performance, it is an essential consideration, especially if you plan to work in an area where noise is a major concern. Sound output can be anywhere from 40-90 dB, and the higher rating, the higher the sound output.
An air compressor with a 75 decibel rating and below is considered tolerable, especially if you are looking for a machine for domestic use. Any machine with 85 dB and over is deemed noisy, and being exposed to this noise level for a long time can be dangerous to your hearing. However, most manufacturers are now producing quiet compressors designed with sound reducing features to offer a lower noise operation.
Air compressor tank specifications (gallons)
The size of the compressor is also an important consideration since it determines how long the compressor can run the air tools before the need to rebuild pressure in the tank. A larger tank means you’ll get a continuous flow of air to get the job done and vice versa. If you intend to use the air compressor occasionally, a 20-gallon of storage space is a good place to start. However, if you will be using tools that require a high volume of compressed air, then you’ll need a larger tank.
The duty cycle of an air compressor is the amount of time it can run before it needs to shut down, and this is expressed as a percentage. For instance, a compressor with a 100 percent duty cycle is designed to run for the entire cycle time without having to shut down. Such compressors have cooling features to prevent overheating, and they are ideal for applications with a constant demand for compressed air. Compressors rated for short run times (below 25 percent duty cycle) are best suited for small tools, and they should not be used in industrial environments.
When comparing different air compressor specifications, always go for a machine that delivers the most CFM, using less horsepower and at the lowest noise level possible. Other aspects like quality and price will definitely come into play but understanding these key specs makes you feel confident when making a purchase decision.