AS-C306 Double Cartridge Mechanical Seal

Background Knowledge：

What is the air film stiffness of the air film seal in the mechanical seal

 The air film stiffness is mentioned in the working principle of the air film seal, which refers to the elasticity of the formed air film. The operational stability of the air film seal is mainly determined by the stiffness of the air film, which reflects the response of the seal to changes in speed. For a given speed increment, when the pressure of the sealing gas is low, the increment of the gap is large; when the stiffness of the gas film is small and the pressure of the sealing gas is high, the increment of the gap is small (the reason for the larger stiffness of the gas film is that when the pressure is low,  the stiffness of the hydrostatic membrane is also lower).

In actual sealing, the value of the gas film stiffness, that is, the stiffness of the fluid dynamic pressure effect, depends on the depth, length and shape of the dynamic pressure groove, as well as the rotational speed of the seal ring and the viscosity of the fluid. In an experiment with a certain specification of 130mm air film seal, when the pressure of the sealed medium is 1MP and the rotational speed is increased from 4000r/min to 16000r/min, the gap increases by 2.58 microns; and when the pressure of the sealed medium is 8MPa，the increase of the gap is less than 17 microns in the same rotational speed variation range. This is because the hydrostatic pressure plays a major role under high pressure.