The Two Main Types Of Hydraulic Seals

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Hydraulic seals are soft rings that allow industrial machinery to convert motion from a fluid form to a linear one by separating or blocking liquids. This blocking of liquids means that the force used to move the liquid stops at a point and becomes linear rather than fluid. These seals can come in a variety of materials, but their function can be separated into two main forms - static seals and dynamic seals.


Static seals are simply those that do not move while they are in place or fixed on machinery. This means that while the fluid they block may be in motion (due to other parts of the system) they are consistently blocked off where the static seal is. These seals are used in a variety of applications and are most commonly O-rings when used. For example, a static seal may be used in cartridge valves as a way to prevent fluid from each valve from reaching the other valves. These seals are meant to withstand constant, unchanging pressure on at least one side but not friction from movement. Sometimes these seals can be added on top of stronger metal rings for strength in high-pressure environments, as they are typically soft and made of plastic.


Dynamic seals are those that handle the separation of fluid that moves within the container or system that it is in. This means that it's subject to the friction of motion both from the fluid itself and from the movement of the mechanical parts of the system. These rings are frequently used in engines as the pistons move pressurized fluid inside cylinders. There are also wiper rings, which are dynamic seals that prevent contaminants and excess material from entering the cylinder with fluid inside as the cylinder moves up and down in space. Unlike static rings, which are rarely made from metal but may have metal rings attached for stability, these seals can be made from metal, such as steel and bronze. This is because some applications of dynamic seals do not need the flexibility that soft rings provide but instead added durability, such as with piston rings.

There are many different applications that hydraulic seals can provide and many different kinds of hydraulic seals. The two main types of hydraulic seals are static and dynamic. Static seals are stationary and handle pressurized fluid that does not move within the cylinder or other space. Meanwhile, dynamic seals are those that handle movement either of fluids or machinery or both. The type of seal that you need will depend on the machinery you need to be sealed from leaking fluids or external contaminants.

To learn more about hydraulic seals, contact a business near you.