Hydraulic seal

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A hydraulic seal is a relatively soft, non-metallic ring, captured in a groove or fixed in a combination of rings, forming a seal assembly, to block or separate fluid in reciprocating motion applications. Hydraulic seals are vital in machinery. Their use is critical in providing a way for fluid power to be converted to linear motion.


Hydraulic seals can be made from a variety of materials such as polyurethane, rubber or PTFE.[1] The type of material is determined by the specific operating conditions or limits due to fluid type, pressure, fluid chemical compatibility or temperature.[2]


A static hydraulic seal is located in a groove and sees no movement - only sealing within its confined space, acting like a gasket.To achieve this the gasket should be under pressure. The pressure is applied by tightening of the bolts.


A type of dynamic hydraulic seal called a rod seal is exposed to movement on its inner diameter along the shaft or rod of a hydraulic cylinder. A type of dynamic hydraulic seal called a piston seal is exposed to movement on its outer diameter along the tube or bore of a hydraulic cylinder.


  1. ^ "Basics of Hydraulic Seals - Seal Materials". HydraulicFacts.com. The Lubrizol Corporation. 28 February 2013. Archived from the original on 2013-05-03. Retrieved 23 August 2013. 
  2. ^ "PTFE Packing Materials". ptfepacking.net. American Seal and Packing. 28 February 2015. Retrieved 16 Feb 2015.