Based on full factorial design

optimization of structural parameters of a spiral groove dry gas seal (S-DGS) under low or medium pressure was performed. Based on the theory of gas lubrication

the sealing characteristic parameters

such as increase ratio of hydrodynamic open force

film stiffness and film stiffness to leakage ratio of an S-DGS under low or medium pressure were analyzed

and the preferred value ranges of structural parameters of spiral grooves were obtained. The concept of characteristic parameter optimization zone of an S-DGS was presented. The optimum sealing performance with different compressibility numbers of an S-DGS could be properly reflected by characteristic parameter optimization zone. When an S-DGS was operated under low or medium pressure and at high-speed

excellent sealing performance could be obtained for an S-DGS when spiral angle was between 10° and 25° and groove depth was between 5 mm and 10 mm. Excellent hydrodynamic effect and axis film stability could be obtained when groove-to-dam ratio was between 1.5 and 4.0 and groove length-width ratio was between 2 to 8. Excellent comprehensive sealing performance could be obtained when groove-to-dam ratio was between 0.7 and 1.5

groove length-width ratio was between 2 to 5.