Dictionary of Polymer Terminology

Valaq has one of the web's most comprehensive wireline tool dictionaries. More than just a glossary, each term page goes into further detail with insights, real world examples and great related resources.

Back to Glossary

Oil seal


As the name suggest, an oil seal is a component or a device that is used to withhold the oil or lubricant at one place and do not allow it to leak from the enclosure, neither it allows outside particles to move inside the enclosure. Thus oil seals help in saving the fluid inside the closed chamber to remain dirt free.


An oil seal finds its usage in numerous applications and equipment and comes in uncountable range of designs, sizes, shapes and materials. These oil seals are designed and manufactured as per international industrial standards such as AS568, BS 1806, DIN 3771 or as per generic metric sizes and seal types, but it’s always advisable to ask for application specifications and then choose the oil seal that perfectly suits the applications. Many a times, an oil seal has to be designed as per the requirements of the application where it has to be used.

An oil seal working principle is very basic and simple. An oil seal have a flexible lip which is held against the shaft that rotates and exerts pressure on seals outside diameter which in turn touches the casing, a pressure is being created due to shaft rotation on the casing and thus pressurizes the oil seal in between and hold it in place.

Some of the materials used to manufacture oil seals are as follows:

  • Synthetic rubbers
  • NBR or Nitrile
  • Viton FKM or FPM
  • PTFE
  • Polyacrylate (ACM)
  • Silicone (VMQ)