Pressure and Capacity

Continuing on from our previous Blog - How do I know what size compressor I need? We stated in the blog that Pressure and capacity are the two main specifications to look for when buying an air compressor. Pressure means 'how strong' and capacity means 'how much'.

What is Bar/PSI (Pounds per Square Inch)?

These are different terms for pressure used to measure an Air Compressor output. But in this case, it measures air pressure rather than air flow.

What pressure do I need?

In short, you will need enough pressure to provide sufficient force for your application. If your compressor cannot produce pressure at a high enough level, it will not be able to carry out the required task.

The PSI you will need will once again depend on your application and whether you need a constant supply of air. Large Air Compressors used in manufacturing will naturally operate at a higher PSI than a small compressor for household use. Most compressed air equipment is designed to operate at around 90-100 PSI (6-7 Bar). For this reason, most people only need a compressor with a maximum pressure of 7 bar.

If the pressure is too low, tools will not work. Too high, and it can cause unnecessary wear along with higher energy bills. As with flow, your best bet is to request a Data Logging Audit or Energy Audit of your system so that the air compressor engineer can provide a bespoke solution.

Did you know? Every one bar pressure reduction equals about 7% energy savings

What is atmospheric pressure?

This is the pressure exerted by the atmosphere. Although we are not aware of the atmosphere exerting a pressure on us, it does so!

What is gauge pressure?

This is the most commonly used value in the compressed air industry when referring to the pressure in a system or equipment. Compressors provide that the increase in pressure. A pressure gauge senses the increase in pressure and indicates it on a scale that for convenience starts at zero. Pressure gauges measure the pressure above atmospheric pressure.

A conversion widely used in the compressed air industry is: 1 bar = 14.5psi. A useful rule of thumb: 7 bar = 100psi