S.S. Borosilicate Sight Glass

Fittings, parrots, packing, tooling and so on.

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Rain Distillate
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Re: S.S. Borosilicate Sight Glass

Post by Rain Distillate »

Oldvine Zin wrote:I would just get rid of that sight glass - do you really need it??

OVZ
How do you run a column without it? Before I bought it I was having issues with puking.
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Rain Distillate
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Re: S.S. Borosilicate Sight Glass

Post by Rain Distillate »

She's sealed up nicely with a bunch of tape! Just about done and no leaks
joeymac
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Re: S.S. Borosilicate Sight Glass

Post by joeymac »

any way a teflon Oring would work if you sized it right to squeeze between the stainless and the glass?
"Woe to those who are heroes at drinking wine and champions at mixing drinks" - God (Isaiah 5:22)
So evidently, God wants us to drink our whiskeys single barrel and our Bourbons neat.
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Rain Distillate
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Re: S.S. Borosilicate Sight Glass

Post by Rain Distillate »

The best thing I could find is a teflon crush gasket (ebay) but not sure if they got a 3".
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cranky
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Re: S.S. Borosilicate Sight Glass

Post by cranky »

A while back Bearriver showed me some PTFE rope he picked up on ebay, I thought that would make a perfect seal if I wasn't such a cheap bastard. I have been known to use an entire roll of tape to make sure there is plenty of squish. One thing I found with glass is that the metal parts have a much higher expansion rate than the glass so they have to be pretty tight to insure sealing.
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Re: S.S. Borosilicate Sight Glass

Post by joeymac »

At work we use foamed or compressible PTFE gasket material for situations like this. The 1/8" thick material makes a great improvised sanitary gasket seals when you cant find an actual seal, too! Handy stuff to keep around. In fact, the first column I ever built used a brass/copper plumbing union to attach all the column sections. Using a 3" wrench to make all the giant fittings seal tight was a pain in the ass so I used some of the 1/16" thick compressible PTFE gasket cut into rings and hand tight did the trick. I got dozens of reassembles out of each gasket I made.

It's $4-$7 for a 3" gasket depending on thickness.
https://www.mcmaster.com/#catalog/123/3535/=16yt4d7" onclick="window.open(this.href);return false;" rel="nofollow

If you are worried about dissimilar thermal expansions in most kinds of assemblies then use spring washers (aka Belleville washers or disk springs) on the nuts. You'll have to size the Belleville washer spring constant to be consistent with whatever torque you're using. If the bolt lengthens they spring out to maintain a calculated torque value and if a flange or assembly expands then they compress to avoid bot failure. They can be stacked in parallel or series (or a combination of parallel-series) to achieve desired spring rates.

https://www.mcmaster.com/#standard-disc ... s/=16yt62d" onclick="window.open(this.href);return false;" rel="nofollow
"Woe to those who are heroes at drinking wine and champions at mixing drinks" - God (Isaiah 5:22)
So evidently, God wants us to drink our whiskeys single barrel and our Bourbons neat.
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Rain Distillate
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Re: S.S. Borosilicate Sight Glass

Post by Rain Distillate »

joeymac wrote:At work we use foamed or compressible PTFE gasket material for situations like this. The 1/8" thick material makes a great improvised sanitary gasket seals when you cant find an actual seal, too! Handy stuff to keep around. In fact, the first column I ever built used a brass/copper plumbing union to attach all the column sections. Using a 3" wrench to make all the giant fittings seal tight was a pain in the ass so I used some of the 1/16" thick compressible PTFE gasket cut into rings and hand tight did the trick. I got dozens of reassembles out of each gasket I made.

It's $4-$7 for a 3" gasket depending on thickness.
https://www.mcmaster.com/#catalog/123/3535/=16yt4d7" onclick="window.open(this.href);return false;" rel="nofollow

If you are worried about dissimilar thermal expansions in most kinds of assemblies then use spring washers (aka Belleville washers or disk springs) on the nuts. You'll have to size the Belleville washer spring constant to be consistent with whatever torque you're using. If the bolt lengthens they spring out to maintain a calculated torque value and if a flange or assembly expands then they compress to avoid bot failure. They can be stacked in parallel or series (or a combination of parallel-series) to achieve desired spring rates.

https://www.mcmaster.com/#standard-disc ... s/=16yt62d" onclick="window.open(this.href);return false;" rel="nofollow
:thumbup:
joeymac
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Re: S.S. Borosilicate Sight Glass

Post by joeymac »

Also, can't believe i didn't think about this in my earlier in my response...

When dealing with thermal expansion problems, use differing thermal expansion coefficients to your advantage. For example, you know you have a glass pipe expanding much slower than a stainless threaded rod (probably 316SS). You need to make sure you're using very thick washers of a much greater expansion rate than that of 316 stainless. Why? If the stainless rod is clamping between the two washers, that means if heat causes the rod to expand a little the washer will expand much quicker. Because the washers expand at a greater rate, they are able to quickly take up the slack created by the expanding rod. So effectively, to create a zero-expansion bolt and washer stack up through a wide range of temperatures, you need the length of the bolt and combined thickness of the washers to be INVERSELY proportional to their respective thermal coefficients.

Lets say a bolt is 20cm long and has a 15e-6 m/m-K expansion rate. And you decide to use a polymer spacer standoff as your washer with a 90e-6 m/m-K rate. That's a rate difference ratio of 6:1 meaning for every degree change, the standoff washers can lengthen 6 times more than the bolt. So if you don't want the clamping distance between the standoff washers to change as things get hot/cold, you had better have the standoffs combined lengths be 1/6th the clamp length of the bolt (or 1.6cm long each). Easy. And it's almost that simple in real life, but in our case there is glass material being constrained... so instead of setting our length ratios to to have zero overall expansion, you would want to shorten the spacers just a tiny bit so that the bolt still opens up the whole assembly with heat just a little bit and the gap expands at the same rate as the glass tube.

Using dissimilar coefficients to maintain zero system displacements is quite common in high precision optic assemblies that see significant temperature swings like laser trackers, seeker and jammer ballistic heads, orbital cameras... etc. And nice olde-tyme grandfather clocks, too. :lol:
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"Woe to those who are heroes at drinking wine and champions at mixing drinks" - God (Isaiah 5:22)
So evidently, God wants us to drink our whiskeys single barrel and our Bourbons neat.
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00Speedy
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Re: S.S. Borosilicate Sight Glass

Post by 00Speedy »

Hi,

i found these PTFE Sight Glass Gaskets:

http://destylandia.com/index.php?id_pro ... er=product" onclick="window.open(this.href);return false;" rel="nofollow
http://destylandia.com/index.php?id_pro ... er=product" onclick="window.open(this.href);return false;" rel="nofollow
http://destylandia.com/index.php?id_pro ... er=product" onclick="window.open(this.href);return false;" rel="nofollow

But must buy it together with the Glass.
I'll try it for my 2" Sightglass.... :thumbup:
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rgreen2002
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Re: S.S. Borosilicate Sight Glass

Post by rgreen2002 »

00Speedy wrote:Hi,

i found these PTFE Sight Glass Gaskets:

http://destylandia.com/index.php?id_pro ... er=product" onclick="window.open(this.href);return false;" rel="nofollow
http://destylandia.com/index.php?id_pro ... er=product" onclick="window.open(this.href);return false;" rel="nofollow
http://destylandia.com/index.php?id_pro ... er=product" onclick="window.open(this.href);return false;" rel="nofollow

But must buy it together with the Glass.
I'll try it for my 2" Sightglass.... :thumbup:
WOW! Fantastic find speedy! I looked for about a year!
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