KEVN® O-Ring Rubber Identification Tool


The KEVN® is a practical and useful tool to distinguish between four (4) commonly used o-ring rubber compounds:

  • Kalrez® – Perfluoroelastomer (FFKM)
  • EPDM – Ethylene Propylene Rubber (EPR)
  • Viton® – Fluorocarbon (FPM, FKM)
  • Nitrile – Nitrile Rubber (Buna-N)

The KEVN® is a registered trademark of Global O-Ring and Seal, LLC. All rights reserved.

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How It Works & How to Use It

  • Place the o-ring on a stable table or surface. Hold the KEVN® in a vertical position so that the straight edge of the sliding weight hangs out the bottom of the steel tube.
  • Position the straight edge of the weight on the o-ring’s cross-section and raise the weight all the way to the top of the tube (as far as it will go).
  • Release the weight and let it drop onto the o-ring. The weight will bounce. The height of the first bounce will rise to one of the four calibrated ranges.

Where and When to Use

  • To verify an o-ring just before installing the o-ring in the equipment.
  • To differentiate between KNOWN o-ring materials.
  • To check for mislabeled o-rings.
  • To verify new o-rings.
  • Sorting applications.

Best Conditions For Use

The KEVN® is calibrated to work best with the following:

  • 70 durometer o-rings
  • New and unused o-rings
  • O-rings within their rated shelf life
  • Cross-sections starting with .103” (2.62mm) up to .275” (6.99mm), including the standard AS568 series (100, 200, 300, & 400 series).

Do Not Use For:

  • Identifying or analyzing failed or damaged o-rings
  • O-rings of unknown composition
  • Out-of-date o-rings
  • O-ring cross-sections less than .103″ (2.62mm), or greater than .275″ (6.99mm)
  • Identifying composition of flat gasket surfaces
  • O-rings other than 70 durometer

DISCLAIMER: The use of rubber elastomer names such as Kalrez® & Viton® (which are trademarks of DuPont Dow Elastomers) are for reference only, and does not guarantee that the materials tested with this tool are of these name brands.