Sealing documentation over groove specification?

[Joel_Lapointe]

Hi,
We currently have a x-ring (quadring) seal that leaks. The application is an automotive actuator for offroad vehicles (ATVs...). As it is a x-ring (quadring), design documentation is more sparse than for o'rings. I try to get justification over dimensional tolerances on grooves for those seals. I've found the Eriks handbook on quadrings for general design. However I don't find more details about tolerance explainations. There isn't mush more. Is there some standards on these especially about groove tolerancing to ensure leakproofing? Especially the cylindricity as we have doubts about the ovality of our PBT-30GF plastic part.
Thank you.

 

[TugboatEng]

It is my understanding that x-rings were designed to be a drop in replacement for an o-ring and that all standard o-ring dimensioning and tolerancing should apply.

 

[3DDave]

Many times I have heard "ovality" is the problem, but it's never ovality. It's something else; wear, for example.

 

[Joel_Lapointe]

It is my understanding that x-rings were designed to be a drop in replacement for an o-ring and that all standard o-ring dimensioning and tolerancing should apply.

I just saw a file : https://practicalmaintenance.net/wp...Considerations-and-Maintenance-of-O-rings.pdf.
It says the following :

AS shown in above figure, with X-rings, the standard grooves are deeper in comparison with O-ring glands. So the diametrical squeeze is lower in X-rings than with O-rings. This makes dynamic sealing possible with reduced friction. In the situation that an O-ring rolls in the groove and creates torsion, a X-ring slides with no negative results.

So this adds to my willingness to get access to "standard" practices for quadrings.

 

[3DDave]

"Testing" is the word you are looking for. The lack of standard practices is due to the proprietary design of the seal.

Reduced friction = increased leakage.

 

[btrueblood]

Quad rings have the advantage (for suppliers of them) that they can withstand far less wear than a regular o-ring before leaking.

 

[dtimberlake]

I believe there are some surface finish requirements amongst the Groovy specifications.

I'm thinking a dynamic seal really needs lubrication.

Is the actuator pressurized by air or oil?

What is the actuator maximum pressure ?