Bellows of the PSS Shaft Seal.

The PSS Bellows offer the best combination of durability, strength & elasticity, and in addition to carrying standard sizing, can be engineered in a number of configurations to meet various application requirements. The most common configuration is composed of two ends (connectors) and a convolution region where the ends provide the assembly interface and the convolution (bellows) region provides for the design application travel / required flexibility. The application dictates the material requirement with standard options available in Nitrile or Silicone.

Nitrile Bellow

Nitrile rubber PSS Shaft Seal bellow

Nitrile rubber's single most important property is its exceptional resistance to oils and non-polar solvents. It also offers good gas impermeability, abrasion resistance and better thermal stability than most general purpose elastomers.

Chemical Composition (wt%)

Hardness Shore A Tensile (MPa) Tensile (psi) Elongation
60 - 90 13.8 - 14.5 1,455 - 2,100 150% - 400%

Mechanical Properties Spec.

Typical applications: Oil resistant seals that may be exposed to daylight or other forms of radiation.
Advatanges: Good resistance to oils. Improved ozone resistance.
Upper continous service temp: 100°C
Min. temp. for sealing applications: -20°C
Min. non-brittle temp.: -30°C
Nitrile PSS Shaft Seal bellow

Silicone Bellow

Silicone PSS Shaft Seal bellow

The silicone bellow material meets and exceeds the properties listed in SAE J20 Class A and provides superior low and high temperature resistance. The bellow is reinforced with multiple plies of aramid fabric and the Fluorosilicone Cover creates an oil and fuel resistant barrier protecting the exterior surface from the possibility of damage from splash or spill.

Original Properties

Temp. Range: -55°C - 175°C
Durometer, points Shore A: 55 - 75
Tensile, min, MPa: 5.5
Elongation, min, %: 200
PSS silicone bellow closeup

Oven Aging Conditions

Change Limits: 70 hours / 175°C
Durometer, points Shore A: +10
Tensile, max %: -15
Elongation, max, %: -40

Oil Immersion Change Limits

Change Limits: 70 hours / 100°C
Volume, max %: 0 - +45
Tensile, max %: -40

Coolant Immersion Change Limits

Hours at Boiling Point: 70 hours
Volume, %: 0 - +40
Durometer, points Shore A: -10 - +10
Tensile, max, %: -30
Elongation, max, %: -25

Compression Set °C

70 hours, max, %: 40
Cold Flexibility (°C): -40

PSS silicone bellow closeup

Polyestor / Aramid Fiber

Width: 91.4 cm
Thickness: 0.48 mm
Tensile Warp Wise: 648 N
Tensile Weft Wise: 610 N
Elongation Warp Wise: 15.7%
Elongation Weft Wise: 17.4%