Abstract: For improving the energy application of pressure reduction by expander in high pressure pneumatic system, the pressure reduction with classification control is proposed. It is a useful energy saving method proved by the energy compensating principle and property under the equal pressure condition. The mathematic model, the simulation and the experiment of the two steps control system are completed. The results show that the theoretical model approximately corresponds with the test; and the prerequisite of holding good control performance of the system pressure output is that the output pressure of the first step pressure reducing is higher than the critical input pressure of the second step pressure reducing.

Key words: Classification control, Energy property, High pressure pneumatic, Pressure reduction by expander