[time-nuts] Thunderbolt stability and ambient temperature

Neville Michie namichie at gmail.com
Mon Jun 15 18:08:58 EDT 2009


hi,
the main point of the water approach was the high performance of  
water as a heat storage medium.
Quartz, if one can assume that is what pebbles are made of, has a  
density of 2.7 g/cc but a specific
heat of only 0.2 cal/gm C.
That is only 0.54 cal/cc C compared to water with a figure of 1.0.
So water still has greater merit as a thermal buffer.
Cheers, Neville Michie





On 16/06/2009, at 2:30 AM, Joseph M Gwinn wrote:

> time-nuts-bounces at febo.com wrote on 06/15/2009 06:57:13 AM:
>
>> They suggest you add a small amount of chlorine bleach to water
>> containers you store for natural disaster emergencies. You also need
>> to replace the water on a regular basis even with the bleach in it.
>> Here in Christchurch, New Zealand, they don't even chlorinate the
>> water we drink, it comes straight out of a natural aquifer underneath
>> us. As for the long term effects of bleach on plastic bottles, one
>> would imagine that it would accelerate the breakdown of the plastic.
>> Interestingly, someone in the know, talking about land-fill sites,
>> suggested that there is essentially no breakdown of these items when
>> they are fully embeded in the fill. Luckily we recycle almost
>> everything here but it would make interesting finds for future
>> archaeologists.
>>
>> A glass vessel with a stabilised rubber stopper or lapped glass
>> stopper and wax sealed would seemingly be better for long term use  
>> and
>> the glass should conduct the heat better than plastic for our xtal
>> oven ballast. But glass is not a solid, it's a liquid after all and
>> would eventually find the lowest point with time. Mind you, that is a
>> very long time. The other thing that comes to mind is that
>> state-change salt type of liquid that absorbs energy well. Of course,
>> you could use an eskey if it was not holding the beer and may be a
>> less smelly alternative than a used fridge at room temp.
>
> I was the one who originally rained on the use-water-in-a-bottle  
> approach.
>  The response was that even a child could store water.  Well, that  
> is not
> the common experience with water-cooled equipment, which always  
> manages to
> require continual maintenance attention, so I went quiet, and  
> listened as
> the subject was explored.
>
> It has become apparent from the issues and increasingly complex  
> schemes to
> solving tose issues that keeping water in its place is not exactly  
> child's
> play, and it seems to me that water is far more trouble and even  
> expense
> than simply getting a big hunk of scrap metal, unless one needs  
> tons of
> thermal mass.  If one needs fast thermal exchange with the air,  
> drill some
> holes or use a set of thick plates with spacers, so the distance  
> from air
> to the most remote part of the mass is no more than an inch or so.   
> Or,
> use a big hunk of copper or aluminum.  Or both.
>
> If one needs tons of thermal mass plus rapid exchange with the air,  
> use
> brick checkerwork or a pebble bed, a standard industrial approach: <
> http://en.wikipedia.org/wiki/Regenerator>.  For thermal  
> stabilization of
> timekeeping equipment, a pebble bed and a circulating fan is cheap and
> easy.
>
> Joe Gwinn
>
>
>> 73,
>> Steve
>>
>> 2009/6/15 Didier Juges <didier at cox.net>:
>>> Here in Florida, we routinely store water in prevision of the
>> next big one.
>>>
>>> Plastic water bottles (any brand) start looking funny
>> (shrunk) after a few
>>> months, and downright scary (as in: you don't want to drink
>> from THAT) after
>>> a year or so.
>>>
>>> It seems the gallon jugs do somewhat better than the smaller
>> bottles. I had
>>> jugs that still looked OK after a year, but not good after
>> two. The pastic
>>> seems much thicker, and maybe it slows down the process?
>>>
>>> It's been like that for as long as I have lived here, i.e.
>> since 1985. I do
>>> not know if it is related to the climate. It makes no
>> appreciable difference
>>> if the water is stored in the garage (no A/C) or in the house.
>>>
>>> Didier KO4BB
>>>
>>>> -----Original Message-----
>>>> From: time-nuts-bounces at febo.com
>>>> [mailto:time-nuts-bounces at febo.com] On Behalf Of Thomas A. Frank
>>>> Sent: Saturday, June 13, 2009 12:16 PM
>>>> To: Discussion of precise time and frequency measurement
>>>> Subject: Re: [time-nuts] Thunderbolt stability and ambient
> temperature
>>>>
>>>> More to the point, you will be disappointed to find the bottles  
>>>> will
>>>> NOT last that long.
>>>>
>>>> Cleaning out the cupboard recently, I can across some bottled water
>>>> that had 1998 date codes.  Several had leaked, but one was still
>>>> intact enough to show the likely problem.  It would appear that  
>>>> over
>>>> the past 10 years, the gases dissolved in the water migrated  
>>>> through
>>>> the plastic (or the cap seal), resulting in a vacuum forming in the
>>>> bottle.  This distended the bottles and caused structural failure.
>>>>
>>>> Either that, or the water caused the plastic to shrink.
>>>>
>>>> Glass would probably fair better.
>>>>
>>>> Tom Frank, KA2CDK
>>>>
>>>
>>>
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>>
>>
>>
>> -- 
>> Steve Rooke - ZL3TUV & G8KVD & JAKDTTNW
>> A man with one clock knows what time it is;
>> A man with two clocks is never quite sure.
>>
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>> Thunderbolt stability and ambient temperature)
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