[ Jody asked his friend, George Goble, at Purdue University, for
 [ further information about refrigerants. ]

 --- forwarded message, please reply to sender and MMD ---

 [ In Digest 980410 Richard Vance wrote: ]

> Prior to [using] Freon(tm) in the late thirties, SO2 was usually used
> in small refrigerators because liquefied NH3 (ammonia) gas is very
> hazardous, as opposed to the liquid ammonia NH3OH (ammonia water) we
> are familiar with.
>
> If it gets on the skin, or is breathed, it causes terrible burns by
> leeching out the H2 and O2 from organic material.  Also, it can break
> down and burn in certain circumstances.  SO2 only stinks if it leaks
> out.

Freon was invented in 1929-1930 era, but didn't get widely commercial-
ized for another 10 years.  Ammonia requires all steel pipes/parts that
must be welded, not soldered or brazed.  No copper allowed.  I think
methyl chloride was also used then.  Along with DME (dimethyl ether)
and butane/propane and other flammable hydrocarbons, methyl chloride
is pretty toxic.

> NH3 is still the best refrigerant, but it is impractical for small,
> isolated units.  In large installations, the chiller unit is usually
> in a safe, isolated area.  The liquefied gas is evaporated in a heat
> exchanger, which cools a brine that is piped to the various cold
> rooms, ice machines, or freezers throughout the plant.
>
> Richard Vance

This is correct.  Purdue Univ. closed it's ice rink because the
physical plant could not keep the ammonia system running, due to
lots of leaks in the compressor room.

George H. Goble

 [ I have known George for years and would describe him as having a
 [ passion for materials that boil at low temperatures.  He holds a
 [ patent for a non-ozone-depleting substitute for R-12 which is
 [ approved for automotive use:
 [
 [      http://www.autofrost.com/
 [
 [ George is also known for his exploits with liquid oxygen at the
 [ Purdue engineering fraternity's annual barbecue:
 [
 [      http://ghg.ecn.purdue.edu/
 [
 [ Thanks for writing to us, George!
 [
 [ Jody