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Sealing sight glasses


rtshfd

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I have a single sight glass on my vodka column that just won't seal and play nice. It consists of two silicone gaskets, a sight glass and threaded frame that screws down on top of the glass which is sandwiched between the gaskets.

Are there any tricks anyone is willing to share in order to correctly seal this setup?

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I have a single sight glass on my vodka column that just won't seal and play nice. It consists of two silicone gaskets, a sight glass and threaded frame that screws down on top of the glass which is sandwiched between the gaskets.

Are there any tricks anyone is willing to share in order to correctly seal this setup?

Only one gasket should be needed to create a seal. Presumably the one on the outside is just protecting the glass from the threaded frame by providing a cushion or something? This means that half the force/compression of the threaded frame is going into a gasket that is not providing a seal. So potentially you have a useless gasket on the outside that is stealing sealing force from the inside one.

On my still the metal screw part pushes directly on the glass.

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Like Hedgebird said on my stills as well. One gasket between the glass and the column. It should be pyrex(hard glass), and it can take a bit of pressure and metal contact without worry, as opposed to soft glass or tempered soft glass that will shatter on you.

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you'll have to wait till everything is cooled down, but pull the sight glass apart and dry the glass and both inner and outer seals.
insert inner seal, and glass, damp outer seal and insert into retainer ring and tighten on.
the dry inner seal and glass should not rotate, while the wet outer seal should slip easily.
this will allow you to bed the glass and seal tigtly.
any rotation of the glass and seal can cause the seal to unseat, or fail to seat properly.

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Good idea Roger. If there's a tad of resistance on the threads some lubrication could allow the cap to go on a little more snug.

I'd also check the flange to make sure it's true.

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