1) Axle Diameter: The size of mechanical seal is usually 6-200 mm, especially up to 400 mm. Axle diameter of pump is usually determined by strength requirement to be rounded or adjusted by sleeve to meet the specifications of mechanical seal.

2) Speed: The speed of centrifugal pump is usually the same as that of pump. The speed of mechanical seal plant of centrifugal pump is usually less than or equal to 3000r/min; the speed of high-speed centrifugal pump is less than or equal to 8000r/min, especially the pump is less than or equal to 4000r/min.

3) Uniform circumferential linear velocity of sealing face: refers to the circumferential linear velocity of uniform diameter of sealing end face. The sealing surface has uniform linear velocity, which causes greater wear and tear to the thermal mechanical seals of the sealing surface (i.e. the conflict pair). Usually, the circumferential linear velocity of connection and unloading seals is less than or equal to 30m/s; the circumferential linear velocity of mechanical seals using spring stop type seals is less than or equal to 100m/s; in particular, it can be less than or equal to 150m/s;

4) End specific pressure: End specific pressure Pc is the contact pressure (MPa) accepted on the sealing surface. The specific pressure of the end face seal should be controlled in a reasonable scale, too small will reduce the sealing performance, and too large will aggravate the heat and wear of the sealing cover. Reasonable end specific pressure of mechanical seal for pump: Installed mechanical seal, usually Pc=0.3-0.6 MPa; Outside mechanical seal, Pc=0.15-0.4 MPa. When the lubrication is good, the specific pressure of the end surface can be increased appropriately, and the specific pressure of the end surface can be increased for the liquid shadow with bigger viscosity. It can be taken that Pc=0.5-0.7 MPa should be smaller for volatile and worse lubrication liquids, and Pc=0.3-0.45 MPa should be taken.