Hydraulic & Fluid Seals

this seal design is unstable 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 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.

Fig. 1 Cutaway view of a symmetrical seal	Fig. 2 Uninstalled view of a symmetrical seal	Fig. 2a Installed view of a symmetrical seal

Seal Design:

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 low friction, low wear and poor low-pressure sealing capabilities.
• Squeeze seals typically incorporate an energizing rubber element and are generally characterized by high friction, high 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 bidirectional piston sealing applications.

Lip Geometry:

• Beveled seal lip or chamfered seal lip. 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 the bearing and seal lubricated (Fig. 6).

American High Performance Seals designs and manufactures some of the most durable hydraulic seals utilizing advanced materials engineered specifically to offer maximum durability and sealing performance. We provide a comprehensive range of seals and material options to meet industry’s challenging fluids, temperatures, surface speeds and pressures.