Figure 2: Typically shaped oil seal and component nomenclature
Where loads are light, the outer skin layer can be made of silicone. It can be made of Fluroelastomer (orViton) to protect under high temperatures (more than 120 degrees Celcius). The skin can also be made of Poly Acrylate or Polytetra-FluroEthylene.
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ERIKS type GV (type C according to DIN) is equivalent to type M, but is a heavy-duty version with a double metal casing. This can be a useful solution with larger diameters in more demanding applications. There is also a version of this type with a dust lip; the GVST (type CS according to DIN).

5. TYPES OF FLUID: Numerous oil seals can interact with oils, fuels, grease, water and more. However, know exactly what type of fluid the rotary shaft seal will be in contact with will ensure the longevity of the seal and the machinery.