Sizing Your Rubber O-Rings

Step 1

Inside diameter, or ID, measures the space inside the inner edges of the o-ring. This measurement determines how large the opening of your seal may be. Use a ruler to measure from one inside edge to another on a flat surface. Depending on the size, this measurement could be in millimeters or inches.

Step 2

Measure the Cross-Section. The cross-section, or CS, is the width or thickness of the seal. The best way to measure this is with a vernier caliper. Place the o-ring in the caliper without squeezing it to get this measurement. This measurement is essential as the width of the seal helps to determine the O-R's abrasion resistance, compression resistance, and volume well.

Step 3

Even if you are unfamiliar with o-rings, you know that every rubber material has a different hardness. The Shore A durometer scale measures rubber materials. With rubber, the harder the compound, the harder the durometer. Standard rubber compounds usually have a 70 Shore A hardness, but they can differ dependent upon the material and the application. APG can help you determine hardness if you are unsure.

How To Install An O-Ring.

Once you have confirmed that your lubricant is safe for use with both your oring and your application, it is a good practice to double-check the o-ring size. The wrong size can lead to a damaged seal, poor performance, or a damaged system...

5 Factors To Choosing The Right O-Ring

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