Air compressors come with different numbers and ratings which represent their capabilities. While some people see them as confusing, keeping track of what these ratings mean can help you when choosing a compressor hire. The following are the most important ratings which you should strive to understand because they affect the quality of work output of the compressor.
Cubic Feet Per Minute This refers to the volume of air which is delivered to the air tool by the compressor. Cubic feet per minute (CFM) is by far the most important compressor rating. Generally, compressors that have higher CFM ratings deliver more air to the air tool and as such more effective for larger jobs.
Standard Cubic Feet Per Minute This metric compares with CFM, but it is a larger number than CFM. When calculating scfm, the air volume is expanded to a standard level in order to factor in pressure, humidity, and pressure variables. Many users do not run their compressors nonstop therefore, the most important air consumption ratings for them are based on the duty cycle.
Duty Cycle Reciprocating air compressors operate in a cyclical manner with a series of on and offs. Duty cycle refers to the relationship between the on and off time. Compressors are usually rated for a particular duty cycle, for instance 75/25 or 50/50. A 75/25 duty cycle rating means the compressor is designed to run 75% of the time and goes off 25% of the time. For the 50/50, the on time is equivalent to the off time.
Horsepower This is the work capacity of the engine or motor responsible for driving the compressor pump. This rating is one of the most readily recognised by consumers. Compressors with higher horsepower also have greater CFM output. Gallons This rating is an indicator of the tank size of the compressor. If you are hiring the machine to use with tools requiring a continuous airflow such as sanders or spray guns, the gallon is an important parameter. Larger tanks are more preferable for longer jobs because the compressor will run for a much longer period before pausing to rebuild pressure within its tank.
Pounds Per Square Inch Abbreviated as PSI, this is the measure of air force the compressor delivers. Most air tools will require a PSI of about 40 or 90 to do the job. Apart from the ratings above, you should also do comparisons from one brand to another so that you can get a compressor with a reputation for quality work output.