Delivering Fluid Sealing Solutions Since 1972

How to use an O Ring Tester

What is the purpose of an O Ring Tester?

The O Ring Tester is a device used to approximately advise the shore hardness of  Viton™ (or FKM/FPM), Kalrez® or other Perfluoroelastomer (FFKM), Nitrile (NBR) or Ethylene Propylene (EPDM). It indicates the material composition of 100, 200, 300 and 400 series O-rings of 60 to 80 Durometer. Furthermore, O Ring Testers also:

  • Verify an O Ring at the moment of installation
  • Check for mislabelled O Rings
  • Verify new O Rings
  • Sorting applications
  • Differentiate between known O Rings
  • Sturdy stainless steel tubular construction is safe to carry in toolboxes
  • Pocket clip for easy access

O Ring Tester

How it works:

The tester itself is a tube with a controlled or specific weight inside it. The weight falls at a controlled distance. To determine an O Rings rubber compound:

  1. Place the O Ring on a stable table or surface.
  2. Rotate the tool until the weight is at the top of the tube (as far as it will go)
  3. Place the tester over the O Ring
  4. Release the weight and let it drop onto the O Ring
  5. It will bounce. The height of the first bounce will rise to one of the four calibrated ranges.

The highest is Ethylene Propylene (EPDM). The next is Nitrile (NBR). The next is Kalrez® or other Perfluoroelastomer (FFKM). The lowest graduation is Viton™ (or FKM/FPM). This indicates your rubber compound.

The height of the FIRST bounce indicates the O Ring:

Highest Graduation — EP ethylene propylene O Rings are compatible with most water based chemicals from 70 º F to +300 º F.

Third Graduation — Nitrile (NBR). Also know as Buna-N. These O Rings are good for most plumbing applications from -30 º F to +225 º F.

Second Graduation — Kalrez® or other Perfluoroelastomer (FFKM). Also known as perfluorocarbon, compatible with most aggressive chemicals from 0 º F to +600 º F.

Lowest Graduation — Viton™ (or FKM/FPM). This composition is also called fluorocarbon. Viton™ (or FKM/FPM)O Rings are generally compatible with most petroleum-based liquids from -15 º to +400 º F.

The results obtained through the use of this device have been consistent and repeatable in our evaluations. However, since a degree of user technique is required, we cannot be responsible for specific results.

M Barnwell Services supplies O Ring Testers to industry. Contact a member of the team today to purchase or know more.

E & OE. M Barnwell Services endeavours to make sure that all content is correct. Information has been gained from manufacturing partners.

Viton™ is a trademark of The Chemours Company FC, LLC. M Barnwell Services does not manufacture Viton™ products. There are many grades of DuPont® Viton™ that we have available such as Viton™, Viton™ A, Viton™ B, Viton™ GF, Viton™ GLT, Viton™ GFLT, Viton™ ETP. Common colours include Black, Brown and Green in a variety of shore hardness.