Why not Viton gasket for fuel level sensor / access plate?

[thinkn9a]

I see Viton gasket was mentioned several years back, but do not see any further discussion. Viton sheet is available and there is a company that makes a gasket for the access plate (did not see one for sensor)

There also appears to be a strong leaning to pro-seal for the application.

Viton would make it easier to remove and maintain the access plate if repair was needed on sensor or tank, however there is that little detail on sealing the screws. I have had cork and Permatext Aviation compound working for almost 15 years and now have a leak at the fitting for the sample / quick drain valve, and need access.

So,
- what has been experience with Viton?
- recommendations and cautions for using Viton?

 

[JonJay]

I don’t see any advantage over nitrile or other rubber gaskets. Vitron is typically used for its abilities to withstand higher temps, like for brake cylinders.
So, cork, rubber, etc…. You’re still risking premature leaks.

 

[DGlaeser]

Viton is an excellent seal/gasket material. I use it everywhere because I run auto gas in my Subaru engine and non-flammable auto brake fluid for my brakes. Rubber and nitride materials break down with those fluids, Viton does not.

 

[htx9a]

For what it's worth, I tried a sheet of 1/16" Viton, and bolts with orings under the heads and it still wanted to leak in between the bolts. A machined face with an oring groove would work well, but a schmear of tank sealant is cheap and easy, if a bit more annoying to remove.

 

[Freemasm]

I see Viton gasket was mentioned several years back, but do not see any further discussion. Viton sheet is available and there is a company that makes a gasket for the access plate (did not see one for sensor)

There also appears to be a strong leaning to pro-seal for the application.

Viton would make it easier to remove and maintain the access plate if repair was needed on sensor or tank, however there is that little detail on sealing the screws. I have had cork and Permatext Aviation compound working for almost 15 years and now have a leak at the fitting for the sample / quick drain valve, and need access.

So,
- what has been experience with Viton?
- recommendations and cautions for using Viton?

In general, a gasket likes a fairly even force around its periphery to keep the seal compression consistent. The bigger the opening, the more those effects are felt. So, faying surfaces have to be made rigid and/or lots of closely spaced fasteners. Both add weight. The majority of our construction materials and assembly technique just aren't a good match.

 

[pa38112]

The cover plate is not rigid enough to provide good sealing forces between bolts. You could try it with a machined backing ring.

 

[thinkn9a]

So,….answers are all over

but why would Viton be worse than cork or rubber, both of which work for “some“ period of time……
and and if ok in near term, why wouldn’t the time before failure be longer for Viton

 

[Freemasm]

So,….answers are all over

but why would Viton be worse than cork or rubber, both of which work for “some“ period of time……
and and if ok in near term, why wouldn’t the time before failure be longer for Viton

I read it differently than you. One person is possibly using a viton gasket where you desire and for an undetermined amount of time.

Florine based elastomers are a great material when properly applied. Viton is Dupoint's TMed version IIRC. A Viton static O-Ring in a gland has pretty infinite life if properly applied. The joint you're asking about is not rigid. Some parts/areas of the sealing material will be under more pressure (closer to fasteners) than other areas. Don't want to use the word "flow" but conceptualize the polymer as doing such from areas of higher pressure to lower. The joint leak will eventually leak and replacing the seal will be PAINFUL. Your build. Do as you like.

 

[gasman]

The cover plate is not rigid enough to provide good sealing forces between bolts. You could try it with a machined backing ring.

That is why pro-seal has been the go to way to glue the plate in place and still be able to service it in the future.

 

[thinkn9a]

experimental,…. So, I went with Viton.

Access plate was easily serviced without removing tank from wing

p.s. The old cork gasket was still in fair shape and came off easily in ONE piece. In picture old from tank is on top, spare, never used below, with Viton below that

 

[[email protected]]

That is why pro-seal has been the go to way to glue the plate in place and still be able to service it in the future.

I'm in agreement.
I will always be going with the easy, fastest, surest, way of sealing.
Proseal for me. It's easy to remove with a heat gun and not very difficult to clean up. Had to many "gaskets" leak over time.
But I've only been a mechanic for 55 years so have a bit to learn.
My luck varies FIXIT

 

[Ruready]

Viton leaks in below freezing temps, buna does not and buna is fuel resistant
.

Buna vs. Viton: Which Seal for Your Application?​

As a sealing option, the crucial difference between Buna and Viton is the temperature range of the material’s function. Viton is the choice over Buna for high-temperature applications. Viton seals hold indefinitely at temperatures up to 400°F and can last up to 48 hours at temperatures up to 600°F. Buna is effective to 250°F. However, it can effectively seal mechanical objects at low temperatures to –22°F. Viton seals are rendered ineffective at temperatures below 5°F, with the material becoming hard and inflexible.

Buna vs. Viton O-Rings: A Quick Guide | Manufacturer's Rubber

When it comes to selecting Buna vs. Viton for your sealing applications, material needs will be determined by its intended application.

www.manuf-rubber.com