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T-Lon Solutions

RPI Series Piston Seal

With over 30 years of application Success, the RPI hydraulic piston seal is a proven reliable seal for both low and high pressure systems. The RPI seal is a double-acting filled TLON® PTFE compound with a square elastomer energizer offering premium seal stability in reciprocating applications. The filled PTFE seal ring is manufactured with an interference fit with the bore and optimum compression with the square energizer. This offers excellent sealability at low pressures and high pressures when the cylinder experiences ballooning. The square energizer helps prevent the seal from rocking often experienced with a standard O-ring.

Face Grooves (Optional):

For applications of high pressure rise rates, pressure spikes, and rapid change of direction, the seal is apt to experience blow-by. To prevent blow-by and to energize the seal rapidly, face grooves are added to both sides of the seal.


  • Low seal drag/friction (Minimize energy loss)
  • No Stick-slip (Smooth Operation)
  • Long seal life from T-LON® filled PTFE compounds
  • Available for cylinders up to 45″ diameter


  • Mobile Hydraulic Cylinders
  • Pneumatic Piston Cylinders
  • Agriculture Equipment
  • Hydraulic Valves and Pumps
  • Filling Machines
  • Testing Machinery

Technical Data:

(1) T-LON® seal compound determines allowable pressure and velocity ranges
  • Velocity: Up to 12 ft/s
  • Pressure: Up to 8500 psi

(Function of e-gap and T-LON® compound. Max velocity and pressure cannot be used together)

Most Common:

BRONZE FILLED PTFE (“21” or “22”)

  • Highest Extrusion Resistance (Higher bronze content increases extrusion/wear resistance; I.E. larger e-gap allowable)
  • Good sealability

GLASS FILLED PTFE (“03” or “09”)

  • Good wear resistance for tubes with rougher surface finish (Higher glass content increases extrusion/wear resistance)
  • More chemical resistant but more abrasive on mating components
(2) Loader compound determines temperature and chemical compatibility

Most Common:

NBR SHORE 70 A (“P”)

  • Working Temp. Range -30°F to 230°F (250°F intermittent)
  • Commonly used with greases, aliphatic hydrocarbon mineral and vegetable oils, and various hydraulic fluids


  • Working Temp. Range -50°F to 300°F (400°F steam intermittent)
  • Commonly used with water, steam, water/ silicone/ glycol based fluids, and app’s affected by ozone and weathering.


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Have questions? Our team is ready to help with anything you need. Feel free to reach out.

Contact T-Lon 888.340.TLON