Tandem Sealing

As the aerospace industry moves toward increased use of EHAs (electro-hydraulic actuators), higher operating pressures and temperatures, longer life requirements and alternative surface coatings (e.g., HVOF), the necessity for tighter leakage control has become paramount for maintaining optimal efficiency. While prevalent in flight controls, tandem seal systems can be utilized in other areas where leakage and wear are critical concerns.

Typically, the dual set hardware arrangement consists of a simple, closed (or solid), single-piece design. This type of configuration can produce pressure tapping between the seals, thus adversely affecting performance. In order to improve seal life while reducing friction, the primary seal must be able to vent or relieve the excess pressure back into the system during operation.

Specially designed seals, such as the combination of Greene, Tweed's ESE (primary seal) and Enercam (secondary seal), provide this type of performance in challenging applications. This tandem solution offers superior sealing and wear characteristics as well as ease of installation into dual, closed gland arrangements.