Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Going to try two more options, silicone O-Rings.  Which I do use doubled up O-Rings for the older engines (like B30) but their glass tube is larger and the tube slides into the fitting.  Perhaps these doubled or tripled up will work: they are 6.5mm OD, 3.5mm ID, 1.5mm Width but I think the ID might be to small - unless they stretch pretty good.  The more I think about this approach with these o-rings, the more I think it isn't going to work.

Next up is a 3/16" ID x 1/4" OD High Temp Silicone Tubing I found on a site called ZerksPlus and assuming it hugs the sight glass tube enough it could work.  For the "newer" Empire engines with the smaller tube I believe it is important for the seal to start on the glass and end on the fitting's nipple.  Since the glass rests on the fitting's nipple and doesn't go inside the fitting (like older/larger engines).

Also, I am not 100% sure you would call this sight glass 1/8.  It's just a hair over 5mm.  I am attaching photos of my calipers messuring the glass tube for US fractions, US inches, and (real people) metric.  A 3/16 diameter is 0.188 inches or 4.78 mm.  If anything I hope it is better than that hard stuff I am using from Lowe's that I have to stretch on my screwdriver first.