[PSUBS-MAILIST] Light housing gaskets

[Alan via Personal_Submersibles]

Alec,
good idea using the o-ring on top of the glass. 
I have been searching  on sight glass / gauge glass sites to find the best
gasket for under the lens. PTFE (teflon) seems to be well thought of in
high temperature applications. Not sure of the recommended thickness
but one manufacturer selling site glass spares had 1/16 & 3/32" gaskets.
It is really a miniature view port in construction so I guess the gasket on 
our view ports would be relatively thin if you scaled them down to a light
housing size.
Cheers Alan 

Sent from my iPad

> On 19/04/2017, at 10:06 PM, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> For under the lens I have no gasket. I think the main reason I was breaking lenses on one light but not the other was that in the problem one the cavity for the lens was ever too small and the lens was squeezed by it. The problem seemed to be resolved by re-machining the cavity to enlarge it by just a few thousandths. If that had not solved it, my next step was going to be adding a gasket under the lens. It would need to be very thin, and I was planning to cut it from disposable gloves. But apparently no need. As the top gasket I use the O ring itself. I've chamfered the top edge of the lens cavity and use a triangular sealing pattern for the o ring.
> 
> Best,
> 
> Alec
> 
> 
>> On Tue, Apr 18, 2017 at 10:28 PM, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> Cliff & Alec,
>> just ordering 20 tempered borosilicate lenses at $2-50 each including postage!
>> They will go in the pressure chamber, so I'll know whether I got good value.
>> Just wondering what you guys used as gaskets under the lens.
>> I did have an o-ring under the acrylic lens but are putting a gasket under the glass.
>> I have an o-ring in the bore of the lens housing but would like my gasket to be a
>> secondary seal as well as seat.
>> Alec, with your experience of lenses breaking, I am looking at a suitable thickness
>> of neoprene or similar for the top gasket that I can compress to half it's thickness
>> when bolting the housing together. This will give me a bit of machining tolerance.
>> see attachment
>> Alan
>> 
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> 
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