Comparison between displacement and centrifugal compressors The capacity curve for a centrifugal compressor differs significantly from an equivalent curve for a displacement compressor. The centrifugal compressor is a machine with a variable capacity and constant pressure. On the other hand a displacement compressor is a machine with a constant capacity and a variable pressure. Examples of other differences is that a displacement compressor gives a higher pressure ratio even at a low speed, unlike the more significantly higher speed centrifugal compressors. The centrifugal compressors are well suited to large air flow rates.