RECIPROCATING SEALS

What are Reciprocating Seals?

Reciprocating seals are mechanical components used to seal the gap between two moving parts, typically in a piston-cylinder arrangement. These seals prevent the escape of fluid or gas and help maintain pressure within the system. Reciprocating seals are commonly referred to rod and piston seals.  They are very common and used in many applications and industries from industrial to aerospace and medical.  Most piston or plunger spring energized seals utilize an axial reciprocating motion.    

How do Reciprocating Seals Work?

Reciprocating seals work by creating a tight seal between the piston and cylinder wall during the piston's reciprocating motion. The piston mounted seal is mounted on the piston and the dynamic interface is between the piston and cylinder wall. As the piston moves back and forth, the seal prevents fluid or gas from escaping. Some applications require the seal to maintain pressure as the piston moves creating higher pressure.

The rod seal is mounted in the housing and the dynamic interface is between the rod and housing.  The rod seal's primary purpose is to prevent the internal media from escaping. In recent years, some have converted to calling rod seals as “housing mounted” seals. New engineers who may be unfamiliar with hydraulics, can sometimes have a difficult time with the rod seal nomenclature.

Benefits of Reciprocating Seals

Some key benefits of reciprocating seals include:

Reciprocating Seal Materials

Materials used to make reciprocating seals vary depending on the application requirements, but common materials include thermoplastics such as PTFE and UHMWPE.

PTFE

UHMWPE

Reciprocating Seal Selection Considerations

When selecting and designing a reciprocating seal for its intended application, consider the following:

• Dynamic Surface Finish Interface

• Stroke Length and Speed

• Dynamic Material Interface

• Installation - Solid, Stepped or 2-Piece Gland

• Friction (breakout and running)

   

• Temperature (operating, minimum and maximum)

   

• Media/Fluid - Gaseous, Liquid or Paste

• Pressure (operating, minimum and maximum)

• Duty Cycle

Reciprocating Seal Applications

Reciprocating seals are an ideal choice for sealing applications across a variety of industries, including: