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conversion of freezer to refrigerator - Page 2

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Posted by Don T on January 30, 2009, 9:15 pm

 Which two gasses are used ? Which gas in Freezer? Which gas in
Refrigerator? Common household units now, not specialty units. Cite your


Don Thompson

Stolen from Dan:  "Just thinking, besides, I watched 2 dogs mating once,
and that makes me an expert. "

There is nothing more frightening than active ignorance.

It is a worthy thing to fight for one's freedom;
it is another sight finer to fight for another man's.
~Mark Twain

Posted by BradGuth on January 31, 2009, 2:24 am

A heat pump is a heat pump.  Atmosphere could be used as a nifty
refrigerator gas, although most everything uses R22 or the newer
replacements for either freezing or basic refrigeration.  There are
dozens of freon types  including propane, and even weird combinations
to pick from.

Myself, I'd like to see everything switched over to using CO2.

 ~ BG

Posted by cavedweller on January 31, 2009, 1:50 pm
Guess you didn't happen to think that Don T. knew the answer but just
wanted to hear what Harry was going to say?

Posted by harry on February 2, 2009, 9:43 pm
It's possible to use a huge range of gases Chlorinated bi-phenols are
the common ones today.  In days of yore, (19th century) nasty gases
like ammonia, sulphur dioxide and methane were used.  The modern gases
are non flammable and non poisonous.
Having said that, you canbe suffocated in a large release of
refrigerant gas and if it's exposed to naked flame it breaks down to
phosgene gas (used as a poison gas in WW1)  A way of searching for
leaks was to have a blow torch with a hose attched to the air hole.
The free end of the hose was passed along suspect pipes, if there was
a leak the flame turns green (and phosgene gas was produced) So this
way isn't used now.
Here in the UK we used R12 for refrigerators and R22 for freezers.
This is the stuff that allegedly made holes in the ozone layer so the
newer ones mentioned by someone else are used

The actual gas used depends on how cold you want to get.  CO2 is used
infor the idustrial rapid freezing of food for example. Sometimes even
nitrogen. The faster you can freeze it the better it will taste when
everything revolves around the boiling temperature of the gas at the
proposed pressure in the system.  This is controlled in small systems
by the long capillary tube, in large systems by an "expansion valve"
When a system is working flat out, there is near vacuum on the suction
side of the pump.  The pressure side varies depending on the setting
of the expansion valve.
A refrigerations engineer's main tool is a manifold with two pressure
guages he connects into the system.(One each side of the compressor)
The guages give an indication of what's happening, eg if there's a
leak on the system.
Most systems break down due to gas leaks and contamination due to the
electrical insulation in the hermetically sealed motor breaking down,
oil brekdown or water getting into the system    The "lump" in the
pipework between the condenser and the capillary tube is a filter/
dryer to prevent this happening.  (should be renewed if the system is

The essential idea of refrigerators is the the gas within condenses
giving up it's latent heat and elswhere evaporates so absorbing heat.
Otherwise it's not practical.

Posted by BradGuth on February 3, 2009, 4:09 am
Propane works terrific, and it's not the least bit toxic when burned,
nor in sufficient volume as to suggest other factors of safety.

 ~ BG

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