What is an air compressor’s pressure rating?

Air compressors come in many makes, styles and ratings.  One of the most important ratings is the compressor rated pressure.  This is the maximum pressure a compressor should operate, but as many people have found, the compressors will run above their maximum pressure, but should they?

The primary issue is safety — compressors often have pressure vessels within the unit assembly or installed as control storage; these have a rating that should not be exceeded.  The rating is often related to the compressor rated pressure.

Also, one rule of thumb in the industry is that an air compressor will consume about 1% more power for each 2 psi in increased discharge pressure.  If a compressor runs at full load above its pressure rating, because the motors are sized for electrical consumption at rated pressure, the motor will overload, possibly causing damage.

Another issue is efficiency, especially with screw compressors, higher pressure can be achieved by placing the compressor in an inefficient operating mode called modulation. But the problem with this mode is that the cost per unit output goes up substantially, added on to the increased power cost for the higher pressure.  Sometimes you end up paying double or triple for the same amount of air at lower pressure!

Often, the need for higher pressure is caused by excessive pressure losses in piping, filters, dryers, regulators, connectors and hoses.  In many cases, the need for higher pressure is eliminated by replacing an inexpensive, but undersized component.  This can be found and fixed by doing special assessment of your system.

If you are running your system above 100 psi, chances are you have pressure drop problems in your system.  It pays to look for a solution to this costly condition.