Creation of low-speed long-stroke compressor units has now made it possible to obtain quasi-isothermal stages with temperatures of injected gas up to 450K and pressures of one stage up to 12 MPa. The alternative replacing low-flow membrane and multistage compressor units with low-speed ones, offered in this paper, should allow to reduce the weight and size parameters of the unit as a whole by obtaining high pressure in one compression stage. However, unification of such stages for creating multi-cylinder units based on low-speed long-stroke stages has not been discussed until now. The example given in this paper allows to obtain a unified series of low-speed stages for a limited range of parameters. Further development of the unification theme is possible only with the help of optimization methods; extensive experimental and theoretical datahave to be obtained for this purpose.