Air Power not Horsepower

Rental operators should not be fooled by horsepower ratings. More horsepower does not alwaysmean a bigger and better air compressor. This is because some compressors are rated at the ‘peakhorsepower’ of the electric motor and others are rated at the 'running horsepower' of the motor.

Peak horsepower, or developed horsepower, is the highest horsepower the compressor’s electric motor will achieve right before locking up, also known as the breakdown torque.

Running horsepower is the true horsepower rating of the electric motor. This is the horsepower thatwill be maintained during normal use. Air compressors rated at the running horsepower deliver moreCFM than a comparable rated air compressor. Compressors rated using the peak horsepower wantyou to compare horsepower, not air power.

Remember, you buy a compressor to produce air, not horsepower. Air tools require a volume of compressed air (CFM) at a specific pressure (psi) to operate, they do not require a specific horsepower. Remember, air power determines the size of the compressor you need, not horsepower.

Choosing the right air compressor

Factors to consider when choosing your compressor include:

Type:stationary, wheeled portable, hand carry, truck mount, bare compressor, singlestage or two stage.

Volume of air:cubic feet per minute (CFM) and pounds per square inch (psi) of pressure required.

Power/drive:electric or gas driven engines.

Some helpful descriptions of various terms to help you choose the proper compressor are:

CFM:cubic feet per minute. It can be listed as CFM displacement or CFM delivered airto perform your job.

Displacement:this is the volume of air swept through the first stage of piston or pistons and is usually expressed in cubic feet per minute(bore x stroke x compressor rpm).

CFM delivered air:this is the vital rating. It is the CFM displacement x the efficiency of the compressor. This rating varies widely depending on the quality, design and manufacturing tolerances of the compressor.

Delivered air:do not be fooled by incomplete ratings. Air pressure alone does not operate your sander, air wrenches, paint gun or drive a fastener. You need CFM delivered air at a given pressure. While a unit rated by CFM displacement only, or even
by CFM delivered air at a lower pressure may appear to be larger, it may beinadequate for your needs.

Horsepower:air runs your tools, not horsepower. Efficient air compressors consistently produce greater volumes of delivered air. This makes the user moreefficient and saves money. Horsepower can be noted many different ways. The motor or gas engine horsepower rating should not be the deciding factor in the choice of compressor.

Tank size:the tank stores reserve air. It does not help the compressor make more air.A larger tank cannot help if the pump is inefficient or too small. You will run out of air when the stored air has been used.

In order to determine total air requirements:

1)Find the CFM required by the air tools you will be operating.

Find the psi required by the air tools you will be operating.

Compare these requirements to the CFM and psi performance of the air compressor.

For best air tool performance, purchase a compressor with at least one and a half  times more CFM than the air tool requires.

For example, if a ½” impact wrench requires 4.0 CFM at 90 psi, then the air compressor used to operate the ½” wrench should deliver 6.0 CFM at 90 psi. If you plan to run more than one tool at thesame time, you must add the CFM of each tool together to determine your needs. Air tools are rated on an intermittent (start/stop) usage factor. Keep in mind that air tools such asgrinders, sanders and sandblasters are considered continuous running tools and require a largerair compressor, which provides higher CFM. Applying these tips before your next purchase will ensure you pick the right air compressor for your rental operation.

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