March 13, 2022

Preventing Failure in O-Ring Leak Paths

 

Designing something as deceptively complex as an o-ring requires

rigorous testing and attention to detail.

Despite dedicated time and effort, it’s often a challenge

to achieve perfection — unsurprisingly,

o-ring design flaws do periodically occur.

Among the most common o-ring design flaws is insufficient gland volume compared to o-ring volume. That said, by having a thorough understanding of compression issues, engineers can achieve the correct leak path ratio and prevent this failure from occurring in their o-ring applications.

What Causes Overcompression?

There’s a common misconception that rubber compresses volumetrically. This mistake often leads to the creation of seals where the o-ring volume-to-groove ratio is off, allotting too much o-ring

and not enough groove

An o-ring must be displaced in the gland, meaning it must be able to fully fit inside the gland while being compressed. Otherwise, the force to compress the o-ring will increase exponentially. When this occurs, the o-ring won’t fully compress, leading to the creation of leak paths through which the fluid can escape. 

Achieving the Correct Ratio

Overpacking a gland is the source of overcompression issues. An o-ring cannot compress properly if it doesn’t have enough room to expand inside a groove 

A Basic Rule of Thumb for O-Ring Leak Path Ratios:

  • The maximum o-ring volume must not exceed 90% of the minimum gland void

Essentially, you need to make sure that there’s enough room in the groove to contain the entire o-ring. Having enough space allows the ring to expand, fit in the groove, and not fill the entire volume. 

 

Need help troubleshooting?

Contact one of our engineers for assistance.

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