Premature Deterioration of Ozone Diffuser Gaskets – Request for Support

[BSMEclassof2012]

Dear Engineer,


We have recently observed premature failure of the ozone diffuser gaskets. These gaskets are stocked and used accordingly. Operating temperature is around 70 F.


Historically, they have lasted around 3–5 years in service but we have started seeing failures after just 1 year. The material is becoming gummy and is no longer sealing properly.

The Viton used was grade "A".

Can you tell if grade A Viton is chemically compatible for this application? What other factors can be involved that can give this kind of failure?

 

[EdStainless]

If they are the correct polymer my hunch is that the compounder changed some ingredients.
Different fillers (maybe just different brands) or different curative chemcials.
We used to have difficulty in hot water service because of issues like this.
Viton should work and EPDM or silicone should work also.
Provided that your concentrations are not above 20-25%

 

[georgeverghese]

From what I see on Google ( search fake viton gasket), you may be using a generic FKM gasket, and not genuine Viton

"While the term "Viton" is often used interchangeably with FKM (fluoroelastomer), it's actually a trademark of Chemours Company. Therefore, there's no official "fake Viton" manufacturer. However, many manufacturers produce FKM gaskets that may be marketed as "Viton-like" or using generic FKM terminology. The key is to ensure you are purchasing genuine Viton from a reputable supplier if you require specific Chemours quality standards and FDA/USP testing. "

 

[btrueblood]

Viton/FKM chemistry is...weird. The base polymer for FKM is not well controlled, and the chemistry for Viton A is a vinyl backbone which can be problematic with oxygen rich environments and high temperatures. People specify Viton or FKM for high temperature water and steam, when both environments degrade the polymer fairly rapidly, or more rapidly than EPDM. I wouldn't have specified Viton A grade for ozone duty, as Ed said EPDM is a more typical seal for that (and cheaper to boot). Viton A has a low resistance to oxygenated fuels, and Vitons in general don't do well (or, as well as EPDM) in water soluble chemistries. Take a look at the Parker Oring Handbook, they have a lot of data on different polymers and their compatibility with different chemicals. EPDM and FKM are both listed for ozone...but FKM is given a poor rating for ozonated water - so, if there is any possibility of moisture getting to the seals, then the FKM might degrade (ozone can form either basic or acidic chemistry when dissolved in water).