"Bruce L. Bergman" wrote in message
...
On Sun, 15 Mar 2009 13:01:40 +1100, "Grumpy"
wrote:
"Ed Huntress" wrote in message
...
"Richard J Kinch" wrote in message
.. .
Ed Huntress wrote:

R12 knocked holes in the ozone. They've gotten smaller since the stuff
was outlawed in '92 or so.

I guess you haven't been around the third world where they produce and
vent
far more R12 today than we ever did.

Nope, I haven't. It's a violation of law in about 130 countries to fill
a
refrigeration system with it, and its production has been banned or
nearly
so in most of those countries. So it's hard to judge how much actually
is
being "produced and vented" in third-world countries.


I was stunned on a plant trip to Belize. R12 is dirt cheap. They were
casually using it in ways that are literally felony crimes here in the
USA.

Environmentalism: expensive, shoddy, deadly [Schwartz].

Well, again, it's hard to put a number on it. Some international
agencies
that research it say that it's a fraction of what it once was. Keep in
mind that it was being put into cars (and leaking out) to the tune of
something like 10 million units per year, not to mention the other legal
uses before 1994.

Until the Montreal Convention came into effect most of the aerosols in the
world were powered by Freon 12 or a Freon 12/22 mixture.
I was the engineering manager of one small plant that used about 10
tonnes
of the stuff every week. When a spray pack was empty it was thrown away.
Eventually it would be crushed or corrode and the propellant would enter
the
atmosphere. The small amount that ordinary domestic refrigeration units
use
must be insignificant by comarison.

Substitiuting other things for a CFC propellant is a lot easier than
retrofitting refrigeration equipment. And most propellants are
intented to be a total atmospheric loss, so they add up fast in the
'tons released to atmosphere' column.

Not in our case. As the CFC propellants were non-flamable, there was not
flame proof equipment in either the storage or packaging area. To comply
with local regulations would have cost about a million or so. The plant was
shut down and production was shifted to Indonesia, where it was done in a
building with only a roof and no walls. Veltilation was not a problem and
niether were any regulations.




Another company that I worked for in the 1970 had a large refrigeration
plant. One Monday morning we had a complaint that the target temperature
wasn't being reached. Investigation showed that we had lost 15 tonnes of
Freon 22. At that time it cost about $3.50 a kilo! At the same time
ammonia
refrigerant cost about $.50 a kilo. After that, I became a devout believer
in installing only ammonia based refrigeration plant for anything but
small
packaged refigeration.

All well and good, but you REALLY don't want to be around an Ammonia
refrigeration system in a big leak. I like my lungs, and they are
kinda important to my continued everyday living...


If an ammonia plant is properly maintained, majour leaks are unlikely.
Minor leaks are not a problem as the ammonia is so irritating that any minor
leak is immedialty detected. You simply can not stay in an area where the
concentration of ammonia is high enough to cause you physical harm, The
irritation to you nose and eyes is you annoying and painful that you will be
driven out very quickly. In addition ammonia vapour is lighter than air and
will diperse quickly. Freons, on the other hand, are heavy and will pool in
basements and underfloor pipe tunnels. You may not even be aware of the fact
that you are being deprived of oxygen until you collapse.

Of course, if someone drives a fork lift into a 4" ammonia liquid
line............................




Los Angeles has several industrial plants with Ammonia
refrigeration, notably the Baskin Robbins ice cream plant and several
ice skationg rinks. And they occasionally have to evacuate for a
block or more perimeter when a leak happens. It's not something that
should be encouraged if you have a better alternative.

Converting CFC refrigeration over to HFC based systems are fine IF
they take proper precautions - you have to have permnanent leak
detection and a comprehensive plant maintenance program to catch it at
the small leaks stage.

And you don't build up 100 - 250 - 500 tons capacity in a single
machine if at all possible, because that makes the potential for a
huge dump if a pipe cracks...

-- Bruce --