[time-nuts] Thunderbolt stability and ambient temperature
Joseph M Gwinn
gwinn at raytheon.com
Tue Jun 16 11:53:19 EDT 2009
time-nuts-bounces at febo.com wrote on 06/15/2009 06:08:58 PM:
> 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
Yep. But it's runny.
I have a modest proposal to combine the benefits of water and silica: We
will use wine bottles in the bottom of the cooler as thermal masses.
Sadly, any bottle showing any signs of leakage whatsoever will have to be
replaced, the leaking bottle being uncorked and the contents tested. At
> 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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> >> date=Jun 15, 2009 10:59:08 AM; subject=Re: [time-nuts]
> >> Thunderbolt stability and ambient temperature)
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> Thunderbolt stability and ambient temperature)
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