Tag Archives: Types of O-Rings

How to Properly Measure an O-Ring

Measuring an O-Ring is quite simple when you have the right tools at your disposal. All that is required is a clean, level surface; an o-ring; and a measuring device such as a caliper or other measuring tools such as cones, gauges, and size charts.

Directions to Measure an O-Ring

To measure an O-Ring, following the directions below:

  1. Place your o-ring on a flat surface clean of debris.
  2. Determine the inside diameter (ID) and outside diameter (OD) of the o-ring. The o-ring dimensions chart below illustrates where on the o-ring each dimension is measured.
  3. Measuring the width, or cross-section (CS), can be tricky and is measured by lightly pressing the caliper ends onto O-ring as shown in section A-A.

For more information on O-ring sizes click to see the JIS B 2401 Standard O-Ring Size Tables.

Dimensionally specifying an o-ring can typically be done with just two dimensions, the inner diameter (ID) and the cross-section (CS). Occasionally, an O-ring may be specified with an outer diameter (OD) and cross-section or an inner diameter and outer diameter. If two of the three dimensions are known, the third can be calculated using the formulas shown below.

O-Ring Dimensions

O-Ring Dimensions

 

O-Ring Dimension Calculations

o-ring dimension calculations


The original article can be found on Dichtomatik’s website. Gallagher Fluid Seals is a distributor of Dichtomatik, a brand of Freudenberg.

For more information about measuring o-rings or determining the best o-ring to use, please contact Gallagher’s engineering department.

Types of O-Ring Applications

So far on this blog we’ve discussed O-Ring sizes, the materials they’re made from, and the ways in which they can be used.

Types of O-Ring ApplicationsIn this post, we’ll talk about the common types of O-Ring applications, and their impact on O-ring sizing and hardware design.

  1. Static Axial Seals

When designing grooves for static axial seals, the first consideration is whether the pressure is coming from inward or outward.

In situations involving outward pressure, the outside diameter of the groove is primary, and the groove width is the primary consideration for the inside diameter. For inward pressure, the inside diameter is primary. This ensures that the O-Ring needs to move the least distance to seal the extrusion gap.

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