Are you new to the world of compressed air? If you have been hearing terms about the volume of air in an air compressor and getting a bit confusing then these explanations should clarify the differences. The key difference is that displacement is a theory and free air delivered is the actual volume of air.

1. Displacement (volume)
This is the theoretical volume of an air compressor. This is the swept volume of a cylinder multiplied by the number of compressions per minute. This is released in cubic feet per minute (CFM). Do not get the displacement calculation confused with working out the size of air compressor needed.

2. Free Air Delivered
This is a more accurate way of estimating the volume of air that is available. The free air delivered is the volume of air which can be entered into the air compressor. This is released at a specific pressure as CFM/FAD.