Volumetric compressor

A two-stage rotary compressor (10) for gas, in particular air;

• the rotary compressor (10) comprising a bottom plate (20) and a head (30), which enclose, between them, two compression stages ((I), (II));
• the rotary compressor being characterised in that between said two compression stages ((I), (II)) an interconnection device (100;
• 100*;
• 100**) is arranged, which is suited to establish a communication “in series” (100*) or “in parallel” (100**), to be selected by the manufacturer, between said two compression stages ((I), (II)).