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How to Check Valve O Rings

There are several different reasons for why O-rings can fail. Checking for damage is relatively easy. In most cases it is easy to tell that the O-ring does not look normal, but when you identify the exact characteristics, you will know what the problem is and will be able to take steps to fix it. The following four patterns are the most commonly found with O-rings and tells much about the solutions to fix them.

Instructions

1

Examine the O-ring by checking for compression set. This is when the seal lines have become deformed and compressed to the surface and look melted and misshapen. If this has not occurred, continue to the other steps until you can identify the problem. However if it has, it means the material of this O-ring was not suitable, or that the operating system temperature needs to be reduced.

2

Look for extrusion and nibbling. Its characteristics are a "torn," ragged look of the O-ring. This occurs in hydraulic rod and piston seals because of high pressure causing clearance gaps which destroy the ring. If this is the case, you may need to decrease clearance, ensure that the O-ring is tolerant of machine fluid, or replace the O-ring with a harder, more durable one.

3

Check for spiral failure if you have not seen the above two patterns. This looks like the O-ring has been twisted. This occurs when the seal becomes caught on one side but but is sliding and rolling on the other side. This can be fixed by improving surface finish, increased lubrication, or replacing the O-ring with a harder one.

4

Inspect for cracks or splits in the O-ring -- these are signs of explosive decompression. This happens when the O-ring has been operating under high pressure gas, which is then reduced quickly leaving gas trapped within the structure of the O-ring, causing ruptures. To avoid this, slow down decompression time, and select a sealant with resistance to decompression. If this is ineffective, replace the O-ring with a metal seal.

5

Examine the O-rings for abrasion.This looks like the O-ring has been scraped. This occurs when a proper surface finish is not being used. Inadequate lubrication is also a reason -- you may want to use internally-lubricated O-rings. You may need to install filters to avoid contamination of fluid.