fuel tank sight glass sealant

[fourstroke]

Can anyone tell me the best thing to seal a glass sight glass into a fuel tank?
Are any of the silicon type sealants any good? The tank is copper
Thanks
Dougie

 

[mcostello]

"O" rings.

 

[Herbiev]

Only ever used O rings.

 

[deverett]

For those amongst us who know not how, would you explain how you use the O rings for this job.

Dave
The emerald Isle

 

[mcostello]

"O rings" seal by being compressed slightly. They need 2 decently finished surfaces to seal against. Dimensions come from the Internet, Parker Hannifen springs to mind as a source. If You can look at the insides of a modern faucet a lot of them use a O ring to seal them.