Hydraulic & Fluid Seals

Symmetrical Seals

For linear and reciprocating dynamic sealing applications

symmetrical-piston-seals
Symmetrical rod seals
Symmetrical fluid seals

Symmetrical seals are typically centered in the gland and have sealing contact only through the seal lips; therefore,… More info…

this seal design is less stable during cycles, creating rocking and pumping effects which in turn can create leakage and seal damage. The primary reason for the existence of symmetrical seals is its interchangeability between rod and piston applications; same seal can be used as a rod or piston seal. Further, this makes them popular for purposes of stock keeping and reduced inventory.
If, however, you require the best sealing performance and durability, we recommend you select one of our non-symmetrical rod or piston seals depending on your application. These seals have very specific design features that deliver better sealing performance than symmetrical seals do.

Symmetrical Seal Design Considerations:

• Symmetrical Seal Design…

• Symmetrical Seal Design

Symmetrical Seal Design

– Symmetrical seals are seals where the shape of the outside diameter sealing lip is a mirror image of the shape of the inside diameter sealing lip (Fig.1).

– Symmetrical seals are centered in the gland and can be used as either rod seals or piston seals (Figs. 2 and 2a)

– Symmetrical seals that are centered in the gland generally do not perform as well as non-symmetrical rod seals or piston seals do because they are unstable during operating cycles.

symmetrical


• Lip vs. Squeeze Type Seals…

• Lip vs. Squeeze Type Seals

Lip vs. Squeeze Type Seals

The basic design of a seal significantly affects the overall function of the seal, especially at low pressures. One of the most challenging applications is linear dynamic sealing at low pressure while providing low breakaway and running friction. AHPSeals provides a series of low-friction seals for these challenging applications.

– Lip seals are without any energizing rubber elements; therefore, they provide a more flexible dynamic seal lip and are generally characterized by lower friction on the (unpressurized) return stroke resulting in reduced wear and poor low-pressure sealing capabilities.

– Squeeze seals typically incorporate an energizing rubber element and are generally characterized by higher friction, higher wear and good low-pressure sealing. To avoid a pressure trap between two seals and potential seal failure, do not use energizer-loaded seals for back-to-back bi-directional piston sealing applications.

lip_vs_squeeze_symmetric


• Seal Lip Geometry…

• Seal Lip Geometry

Seal Lip Geometry

– Beveled seal lip or chamfered seal lip is the most aggressive seal lip design. Most of our seals feature this lip design as it offers the best fluid film breaking ability, which provides the best sealing performance. Sealing lips for all AHPSeals’ symmetrical seals are precision machined for a sharp sealing edge that cannot be achieved by a net-molding process (Fig.3).

– Knife-edge and straight seal lip designs offer good scraping properties but reduced sealing performance and are used for sealing applications with high fluid contamination (Fig.4 and 5).

– Rounded seal lip is the least aggressive sealing lip and is typically used in pneumatic applications to maintain a microscopically thin oil or grease film to keep wear ring and seal lubricated (Fig.6)

lip_geometry_symmetrical


Application-specific and proprietary seal designs are available. Please contact engineering to get the best seal for your rod sealing applications.


High-Pressure Symmetrical Seals up to 5,000psi (350bar)*

Typical Application

Linear, reciprocating dynamic sealing applications

Operating Range

Pressure: up to 5,000psi (350bar)*. For pressure above 3,800psi (260bar), please contact engineering for clearances. Pressure ratings can be increased by reducing clearances.

Surface Speed: up to 1.6ft/s (0.5m/s)*

Temperature: -40°F to 400°F (-40°C to 200°C) depending on material

Materials: high-performance polyurethanes, NBR (Nitrile), FKM, Viton®, HNBR, EPDM, Silicone, low-temperature, PTFE, Teflon®, FDA-compliant seal material grades and proprietary specialized Duralast™ , Duraloy™, and Permachem™ compounds.

Availability: More Info…

Most standard or non-standard and application-specific designed piston seals, in inch or metric sizes, are available with a 2-4 day turnaround.

Single-acting or Uni-directional High-Pressure Symmetrical Seals capable of sealing pressure from one side


Contact us to request more information or call 1-800-283-7140 for immediate answers to your questions.


Ultra-High Pressure Symmetrical Seals up to 10,000psi (700bar)*

Typical Application

Linear, reciprocating dynamic sealing applications for extended seal life

Operating Range

Pressure: up to 10,000psi (700bar)* depending on material, special designs up to 28,500psi (2,000bar)*.

For pressures exceeding 5,000psi (350bar), please contact engineering

Surface Speed: up to 1.6ft/s (0.5m/s)*

Temperature: -40°F to 400°F (-40°C to 200°C) depending on material

Materials: high-performance polyurethanes, NBR (Nitrile), FKM, Viton®, HNBR, EPDM, Silicone, low- and high-temperature, PTFE, Teflon®, FDA-compliant seal material grades and proprietary specialized Duralast™, Duraloy™, and Permachem™ compounds.

Availability: More Info…

Most standard or non-standard and application-specific designed piston seals, in inch or metric sizes, are available with a 2-4 day turnaround.

Single-acting or Uni-directional Ultra-High Pressure Symmetrical Seals – capable of sealing pressure from one side


Contact us to request more information or call 1-800-283-7140 for immediate answers to your questions.


Long-Life Symmetrical Seals up to 5,000psi (350bar)* 

Typical Application

Linear, reciprocating dynamic sealing applications for extended seal life

Operating Range

Pressure: up to 5,000psi (350bar)*. For pressure above 3,800psi (260bar),contact engineering for clearances. Pressure ratings can be increased by reducing clearances.

Surface Speed: up to 1.6ft/s (0.5m/s)*

Temperature: -40°F to 400°F (-40°C to 200°C) depending on material

Materials: high-performance polyurethanes, NBR (Nitrile), FKM, Viton®, HNBR, EPDM, Silicone, low- and high-temperature, FDA-compliant seal material grades and proprietary specialized Duralast™ , Duraloy™, and Permachem™ compounds.

Availability: More Info…

Most standard or non-standard and application-specific designed piston seals, in inch or metric sizes, are available with a 2-4 day turnaround.

Single-acting or Uni-directional Long-Life Symmetrical Seals– capable of sealing pressure from one side


Contact us to request more information or call 1-800-283-7140 for immediate answers to your questions.


Applications & Industries 

AHPSeals’ seals are currently in successful service in the following industries:

  • Abrasive Substance Pumps and Valves
  • Adhesives Dispensing Valves and Cylinders
  • Automotive Plants
  • Can and Package Filling Machines
  • Cement Industry
  • Chemical Pumps
  • Chemical Pumps and Valves
  • Construction Equipment
  • Cryogenic Liquid Control Components
  • Drilling Equipment
  • Food Processing
  • Government, Military and Defense
  • Heavy Mobile Equipment
  • Hydraulics
  • Liquid Handling Swivel Joints
  • Low Friction
  • Marine
  • Mining
  • Oil-Field Exploration and Production
  • Paint and Solvent Manufacture and Application
  • Pharmaceuticals
  • Presses
  • Rubber and Plastics
  • Space Exploration
  • Steel Works
  • Tire Production
  • Vacuum Service
  • Many other applications

*Maximum values depend on seal material, seal configuration, media, temperatures, pressures, surface speed, dynamic running surface finish and working environment.  Data provided are guidelines for ideal operating conditions.  Seals cannot be operated at their upper pressure and speed ratings at the same time.  For maximum seal life expectancy, do not operate your seal beyond 75% of any of its operating limits. Please consult engineering or call 1-800-283-7140 for advice.


American High Performance Seals assumes no obligation or liability for any advice furnished or results obtained with respect to these products. All such advice is given and accepted at the buyer’s risk.

This information, based on our experience, is offered as part of our service to customers. It is intended for use by persons having technical skill, at their own discretion and risk. We do not guarantee favorable results, and we assume no liability in connection with its use.


Any purchases resulting from information provided by American High Performance Seals, Inc., including proposals, recommendations and quotes, are subject to “AHPSEALS TERMS AND CONDITIONS OF SALE.