If you are in the market for an air compressor, you may feel overwhelmed by the number of choices available. There are multiple factors to consider before purchasing this type of equipment.

The main thing to consider is what your tool requires. Each tool has their own air requirement, measured in cubic feet per minute (CMF); some tools require more than others. While nail guns and staplers use small amounts of air, other tools such as grinders and sprayers consume considerably more.

The necessary amount for your tool is probably printed on its body; if not, check the owner's manual. If you are using more than one tool, be sure to find a compressor that meets the largest cubic feet per minute requirement. It is important to remember that if the air compressor is going to be used for more than one tool at a time, then you need to add up all the equipment's requirements together to calculate what size compressor you need.

When comparing air compressors, it is essential to find the "delivered" CMF, not the "displaced" CMF. The displaced CMF is the cubic feet per minute that is produced when the machine is working perfectly; since this is not possible, the delivered CMF will give you an idea of what you can really expect from the compressor. To be sure you have enough power to use your tools, look for a compressor that meets your requirements, plus 20 percent. This way you can be sure that there will be enough air for your tools to function properly.

Many people believe that you should pick the compressor with the highest horsepower. This is an incorrect assumption. More horsepower does not necessarily mean more air. It is more important to have a quality engine that will produce the amount of air your tools need to work efficiently. When shopping, you need to find the running horsepower, not the peak amount, which is only reached when the machine is started up.

When it comes to air compressors, you can choose from either a stop-start model or a constant-run model. The stop-start variety automatically turns the engine off or on at specified pressure levels. When these compressors are turned on, the tank fills to the maximum pounds per square-inch of pressure and shuts off. Once the pressure in the tank reaches the lowest setting, the motor turns on to rebuild the pressure. With this variety, many people look for the largest tank possible so it will take a long time to use all the air.

With stop-start models the motor can overheat by continually switching on and off, leading to motor damage. By purchasing a constant-run compressor you will avoid this entire issue. With constant-run models, the motor stays on; when the pressure reaching the tank's capacity, the unloader-valve opens to let out some of the air. You may prefer the constant-run compressors if you are going to be using tools that need constant air flow, such as sanders, grinders, or sprayer.