[time-nuts] Thunderbolt stability and ambient temperature
Joseph M Gwinn
gwinn at raytheon.com
Mon Jun 15 12:30:31 EDT 2009
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
> 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
> 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
> >> 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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