Hydraulic Seals

About Hydraulic Seals and Hydraulic Seal Manufacturers Including: Lip Seal, Mechanical Seals, Metric Oil Seals, Oil Seals & Rubber Seals.

A seal is a ring-shaped component that is designed to prohibit or limit the leakage of fluid from a device. Various types of seals are used in applications that have constantly moving equipment, such as the rotating or reciprocating shafts and cylinders that are an essential part of hydraulic and pneumatic systems. Devices that use seals include hydraulic rams and mixers, brake devices, valves, clean rooms, conveyors and test equipment. Hydraulic seal manufacturers generally make their products from are rubber or metal, and in some cases leather or felt. Some of the rubber materials used to create seals are nitrile, silicone, natural rubber, butyl and styrene butadiene. Additionally, quite a few hydraulic seal manufacturers use their own unique materials that they have specially developed for their products.

Different kinds of hydraulic seals exist for numerous purposes and applications. Oil seals are common hydraulic seals. They are used to retain oil and other lubricants in rotary applications and prevent leaks. Many of these operate with a flexible lip that rubs against the shaft or housing to provide a tight seal against leakage. Mechanical seals are used in applications that have a rotating shaft under a state of high pressure, temperature and speed. These hydraulic seals are used to prohibit fluid leakage for such mechanisms as agitators, pumps, mixers and cryogenic seals. Hydraulic seal manufacturers create many products that are application specific and specially designed to prevent leaks under very particular circumstances.

The distinctive types of sealing positions and directions that are used for hydraulic and pneumatic seals are axial seal, rod or internal seal, external or symmetric seal, or piston. The sealing direction is instrumental for hydraulic seals and pneumatic seals in mechanisms that use axial movement, such as cylinders and pistons. Because the action may be single or double, a seal can be used for one or two directions. One of these types, the rod seal, is radial and is press fitted into the housing bore. Another, the axial seal, has the function to axially seal an adjoining housing or other mechanical component.
When purchasing hydraulic seals, there are some important factors to consider, such as the diameter of the housing bore and the inner or outer seal, the dimension of the outer shaft and the axial or radial cross section needed for the application. Also, keep in mind certain operating parameters like the working temperature, vacuum rating and highest working speed and pressure. There are many types of hydraulic seals for different uses in industries. Some of the particular industries that make use of these seals include medical and pharmaceutical, waste disposal, aerospace, marine, food and chemical processing, automotive, military, nuclear and pulp and paper mills.

Hydraulic Seals and Hydraulic Seal Manufacturers Images Provided by Allied Metrics Seals & Fasteners, Inc.

Types of Hydraulic Seals

• Balanced seals are seals that are designed to reduce the effects of hydraulic pressure in the seal compartment.
  
• Bellows seals use a formed or welded bellows to supply a secondary sealing and spring loading.
  
• Bidirectional pressure seals uniformly seal in response to pressure from both directions. Bidirectional pressure seals are also known as "double balanced seals" or "reversible balanced seals."
  
• Dynamic seals stop leakage past components that are in relative motion.
  
• Isolators are a type of bearing seal used in place of oil seals to supply greater reliability.
  
• Lip seals are versatile and high-performance seals used for uniform, low-pressure sealing.
  
• Mechanical seals prohibit fluid leakage around the rotating shaft in a state of extreme pressure, temperature and shaft speed. Typical uses for mechanical seals are for agitators, pumps, mixers and cryogenic seals.
  
• Metric oil seals are available in a wide variety of sizes, all measured in metric units.
  
• Oil seals and grease seals are seals with flexible lips that when placed to a housing or shaft prohibit the escape of fluids or prevent contaminants from entering. Certain grease and oil seals are equipped with a spring to aid in maintaining contact of the seal with the shaft.
  
• O-ring seals are sealing rings that have a circular cross section that is either solid or hollow.
  
• Rubber seals are seals that are made from rubber materials, such as nitrile, viton, natural rubber and hypalon, among others.
  
• Teflon® seals are seals that have been made from Teflon® or are coated with Teflon®. Teflon® is a plastic material that supplies improved lubrication properties, resistance to wear and added strength.

Hydraulic Seals Terms

Abrasion – The surface loss of a material caused by friction.

Abrasion Resistance – A material’s resistance to the surface loss caused by frictional forces.

Adhesion – A state in which two surface are bonded together through interfacial forces.

Axial Movement – Motion along an axis or parallel to the center line of a shaft.

Bellows – A component made from corrugated plastic or rubber around a shaft that has the ability to stretch.

Bill of Material – A list of all materials needed to manufacture a certain product.

Bloom – A change of appearance in rubber, resulting from a solid or liquid material moving towards the surface. Bloom resembles surface dust.

Brittleness – The tendency of a material to crack under deformation.

Conductive – A material's property of being able to conduct/transmit electricity.

Cross Section – The view of an o-ring when cut at a right angle to the axis, which shows its interior construction.

Excluders – Used in a hydraulic or pneumatic cylinder to exclude or scrape the rod clean.

Flow – A material's ability to move in a mold during the molding process.

Friction – The resistance to motion when two surfaces are in contact.

Oxidation – Occurs when a material's surface reacts with oxygen, usually causing a change in the appearance or texture of the surface.

Plug – A conical rubber component pressed into a hole or tube to finalize a seal.

Porosity – The measure of small holes in a material.

Resilience – A material's ability of returning to its original state after deformation.

Shrinkage – The tendency of a material to contract while cooling.

Spacer – A ring with flat sides to provide specific dimensional spacing between two components.

Viscosity – The resistance of a material to flow under stress.

Washers – Round, flat rings used as spacers, gaskets or slip devices under the head of a bolt.