The Difference Between Contact Seals And Non-contact Seals

August 9, 2021
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Dynamic Seal:

(1) The dynamic seal is divided into contact type and non-contact type according to the contact type of the sealing coupling surface. The contact type seal relies on the sealing element to stick to the sealing surface under the action of forced pressure. The sealing surface and the seal are in a state of frictional contact with only a thin layer of oil film spacer; this sealing method has good sealing performance, but due to friction and wear conditions, the relative speed of the sealing surface cannot be too high. This is the case for most reciprocating seals in hydraulics and pneumatics.


Types of Contact-type Confidential Parts:

1. The compression type closes and squeezes the packing in the stuffing box to expand it in the radial direction and press tightly on the shaft or hole to achieve sealing.

2. Pressure-energized seal is a close pair with self-aligning ability. The O-ring and Y-ring in the formed packing seal ring belong to this type of seal.


  • Their working principle is to put the seal ring into the groove and apply a pre-pressure. When the seal is subjected to the pressure of the sealing medium in one direction, the seal is further deformed and the contact pressure increases to adapt to the pressure of the sealed medium The increase to ensure sealing.
  • The non-contact seal is a gap seal. Because there is no contact and friction between the sealing coupling surfaces. This forest seal has low friction and wear, low starting power, long life, but poor sealing. Non-contact seals are mainly used to seal various hydraulic pumps and seals in hydraulic valves to prevent internal leakage. There are many types of non-contact seals such as labyrinth seals and dynamic seals. Labyrinth seals are commonly used in hydraulic components, and the throttling effect in the fluid gap is used to limit leakage. The non-contact seal obtains a fluid dynamic equilibrium state by reasonably designing the pressure of the seal cavity and the size of the sealing surface, and does not involve the sealing performance.