1) Shaft diameter: The shaft diameter scale of pump mechanical seals is usually 6-200mm, and can reach 400mm in particular. The shaft diameter of pumps is usually determined by strength requirements, rounded or modulated with shaft sleeves to conform to the mechanical seal specification shaft diameter;

2) Speed: Usually the same as the pump speed, the mechanical seal factory speed of centrifugal pumps is usually less than or equal to 3000r/min; High speed centrifugal pump less than or equal to 8000r/min, special pump less than or equal to 4000r/min;

3) Uniform circumferential velocity of the sealing surface: refers to the circumferential velocity of the sealing surface with a uniform diameter. The uniform linear velocity of the sealing surface causes significant wear and tear on the heat generating mechanical seal components of the sealing surface (i.e. conflict pair). Usually, the circumferential linear velocity for 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; Especially up to 150m/s or less;

4) End face pressure ratio: The end face pressure ratio Pc is the contact pressure (MPa) received on the sealing surface. The specific pressure of the end face seal should be controlled within a reasonable range. If it is too small, it will reduce the sealing performance, and if it is too large, it will exacerbate the heating and wear of the sealing cover. Reasonable end face specific pressure value for mechanical seals used in pumps: For internal mechanical seals, Pc is usually taken as 0.3-0.6MPa; External type, take Pc=0.15-0.4MPa. When the lubricity is good, the specific pressure of the end face can be appropriately increased. For liquids with high viscosity, the specific pressure of the end face can be increased, taking Pc=0.5-0.7 MPa. For liquids that are volatile and have poor lubricity, a smaller specific pressure of the end face should be taken, taking Pc=0.3-0.45 MPa.