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?
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