How to assemble this compression fitting?

Got a sight glass / thermometer combo from bargain fittings and it includes this compression fitting for the sight glass tube. I ended up unscrewing the compression fitting and some pieces fell out onto the floor. I picked them up, but am not sure how to put it back together. I know that right now the compression fitting leaks right where the tube enters so I can only assume I'm assembling it incorrectly. Anyone have insight here? Thanks!

Ditch the inner metal pieces and use the two o-rings that came in the kit instead.

If you look at this sight it has a picture of how the double ferrules go together under Stainless Steel tube compression fittings. It's the last pic on the page.

Awesome - thanks guys!

Agree, use the orings instead of the metal ferrule. I suppose he includes them because they come with the fitting.

Bobby_M said:

Agree, use the orings instead of the metal ferrule. I suppose he includes them because they come with the fitting.

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Interesting. Yeah two o-rings were included, but I figured they were for the eye bolt to hold the tube. I assembed the compression fitting as shown in the link jsguitar sent and it works great now with a 1/4 turn of a wrench.

What's the benefit of the o-ring over the ferrules? I can see how maybe taking it apart and storage is easier, but this is for my HLT. Not sure I'll be doing that all to often. Thoughts?

mmonacel said:

Interesting. Yeah two o-rings were included, but I figured they were for the eye bolt to hold the tube. I assembed the compression fitting as shown in the link jsguitar sent and it works great now with a 1/4 turn of a wrench.

What's the benefit of the o-ring over the ferrules? I can see how maybe taking it apart and storage is easier, but this is for my HLT. Not sure I'll be doing that all to often. Thoughts?

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The ferrule is really designed to compress into metal...and provides a mechanical seal as it compresses inward...as well as provide a seal against very high pressures.

because the sight glass is more brittle you can't tighten it as much before you run the risk of cracking.

O-rings are much more forgiving for sealing low pressure leaks, and against causing cracks.

if you've got it together with no leaks, then your good!

But for the supplier, in general, people will run into fewer problems with orings

Bumping an old thread, but I can't find an answer. What size oring for 1/2 stainless compression? I'm having a hell of time getting the compression fitting to fit, so I think an oring might be a lot easier.