[time-nuts] OXCO insulation

Brian Inglis Brian.Inglis at SystematicSw.ab.ca
Sun Feb 22 18:12:47 EST 2015


Thought of trying aerogel insulation?
Dust free varieties avoid handling issues.
-- 
Take care. Thanks, Brian Inglis

On 2015-02-22 12:56, Dave M wrote:
> Yes, I'm aware that the newer OXCOs don't have any insulation other than air inside the package.  I failed to mention that in my post.  I am primarily interested in the older OXCOs that have foam insulation inside.  I have a couple of them, including the crystal oven from an old HP 5245L counter that needs new insulation.  The old foam was destroyed by a heater that ran wide open for a while, burning a large portion of it to a crispy mess.
> Bob Camp wrote:
>> A lot of modern OCXO’s no longer use insulation…. the gaps inside are
>> now so
>> small that you get very little benefit from it.
>>
>> On the older parts that do use insulation 2 to 4 pound per cubic foot
>> density
>> urethane foam is a typical choice. You can buy it from most plastics
>> suppliers. It
>> can be machined with just about any tooling out there. The dust is a
>> mess, but
>> it’s not normally considered hazardous.
>>> On Feb 21, 2015, at 7:09 PM, Dave M <dgminala at mediacombb.net> wrote:
>>> What kind of foam insulation is generally used inside an OXCO?  Do
>>> all manufacturers use the same kind?  Is it available in small
>>> (hobbyist) amounts?
>>>
>>> I've read that some folks have used Great Stuff polyurethane-based
>>> insulating foam to repair an OXCO.  I've used it to fill gaps around
>>> pipes in my home, but it's nor subjected to the high heat
>>> encountered in an OXCO. According to Dow's web site, it could
>>> present a fire hazard if subjected to temperature of 240F (115C).
>>> There is a "Fireblock" variety, but it appears to have pretty much
>>> the same formulation as the other varieties, so I can't see any
>>> advantage to it.
>>> Has anyone experienced any long term problems with Great Stuff in an
>>> OXCO?


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