Seals are widely used, from daily life to all fields of industrial machinery and equipment can see the figure of seals. Sealing is mainly divided into static sealing and dynamic sealing. Static seal means that the seal is relatively fixed to the device chamber, while the dynamic seal is relatively moving. For example, the seals of the hydraulic cylinder seal the cylinder wall in the cylinder. If it moves back and forth on the cylinder wall, it is a dynamic seal.

Difference between dynamic and static seals

Static seal is divided into: gasket seal, rubber seal and contact seal.

Dynamic seal can be divided into two types: rotary dynamic seal and linear dynamic seal. The sealing methods are divided into static sealing between relative stopping contact surfaces and dynamic sealing between relative moving contact surfaces.

Static seal: according to working pressure, static seal can be divided into medium low pressure static seal and high pressure static seal. Low and medium pressure static seal usually uses soft material and wide gasket, while high pressure static seal uses metal gasket with hard material and narrow touch width.

Dynamic seal: it can be divided into contact seal and non-contact seal according to whether the seal is in contact with its relative moving parts.

Generally speaking, the contact seal has good sealing performance, but it is restricted by conflict and wear, so it is suitable for occasions with low sealing surface line. In contact seal, it can be divided into circumferential (radial) seal and end face seal according to the touching direction of seal. Face seal is also called mechanical seal.

Non contact dynamic seal has labyrinth seal and dynamic seal. The former has large leakage, and is generally used in the occasions of low sealing and low demand. The power seal includes centrifugal seal, floating ring seal, spiral seal, etc. the pressure difference between the two sides of the seal is counteracted by the pressure generated by the power components to overcome the leakage. It has high sealing performance, but it consumes a lot of energy and makes it difficult for the system to obtain higher pressure.

Non contact seal, because the sealing surface is not in direct contact, the starting power is small and the service life is long. If the planning is reasonable, the leakage will not be too large. However, this kind of seal is operated with the balance of fluid mechanics. If the working conditions change, the leakage will be very large, and this kind of seal can not be purchased in the market.