How to attach a sight glass?

[NickP]

Hi,

I am putting together a brass gas tank that is 1 1/2 inches in diameter. I would like to make one end out of glass. I am wondering what would be the best way to glue the glass to a brass ring that would be soldered to the tank end. I was thinking of silicone, but I don't know if it would hold up to the gasoline.

Any one have any experience with this?

Thanks, John.

Hi John,
As has been intimated by others, in my experience silicone doesn’t hold up well to gasoline/petrol - certainly the silicone tubing used for glow engines becomes very brittle when in contact with gasoline and fails quickly and the same appears to be true for silicone sealants (and your design would require something able to withstand constant immersion). There may be variants designed for full time contact with gasoline but I’m not aware of them and would go with an o ring, JB weld or other epoxy to make the seal.
Good luck! Nick

 

[Peter Twissell]

I would also prefer an o ring.
There is plenty of proper data on the chemical resistance of o ring materials, and with a bolted joint, you have the option to replace it easily in the event of any trouble.

 

[Bruce R.]

Use black windshield urethane, when that stuff sets up nothing will dissolve it.

 

[Longboy]

I use some clear glass carbochons from Ebay and epoxy them into the tube end caps. The excess adhesive can be washed off the glass when still soft using a Q-tip dipped in rubbing alcohol.

 

[Stefan-K]

Excuse me Please, but what is a
"Glass carbochon"?
Never Heard that before and even Google cannot translate it.

 

[awake]

I think the term is "cabochon" (rather than carbochon). The definition is pretty much what you see in the picture - a decorative element with one rounded side - at least, I think that is the definition. Now I'll have to look it up to see if I'm right ...

 

[awake]

Okay, I was close. A cabochon is generally a gemstone that has been polished but not faceted, generally rounded on one side and flat on the other. Think of an old ruby or star saphire or turquoise or such.

I also came up with a definition for "carbochon." It is what many people get when they attempt to cook hamburgers on a grill. They are also rounded on one side, flat on the other, and completely charred all the way through.

 

[MachineTom]

Look in MSC or Mcmaster, dists. all kinds from $10 up.