View single post by Alfred
 Posted: Thu Jul 30th, 2009 05:22 pm
PM Quote Reply Full Topic
Alfred

 

Joined: Tue Mar 6th, 2007
Location: Brewer, Maine USA
Posts: 26
Status: 
Offline
It's interesting to note that every time the space shuttle lifts off, several hundred thousand pounds of Ammonium perchlorate are released into the atmosphere; each booster contains 1.1 million pounds of propellant.  The government doesn't seem too concerned about this fact.

On sweep charging, we did a similar thing years ago (in the 60's and 70's) with GE compressor and sealed system work with no adverse after effects or call backs.  Per GE instruction, we would open the hi side and run the comp, pumping down the low side.  Then, upon closing the hi side purge valve, a small "sweep charge" of a couple ounces was introduced into the system and circulated for a couple minutes.  Then, this charge was purged thru the hi side valve.  I can't remember if it was done in just one sweep, but GE claimed this procedure to reduce non condensibles (air, water vapor, etc.) to be very effective.  I don't recall any call backs on that compressor fiasco GE had in '87 - '88 and we changed dozens.  We also liquid charged (domestic systems) for years, and with a "lo side can", that is, the compressor is in a can at lo side pressure and the suction port is above the sump so as not to pick up oil or liquid refrigerant, we had no problems.  The exceptions were Whirlpool (and possibly others) who used rotary comps where the suction port was brought right out to the suction line - be careful!

As some of you have said, I still prefer a good two stage pump, and when you think about it, with all you must bring in, (scales or charging cylinder, torch set, tool set, filter-drier, compound gauge set....) the trade off between a cumbersome "reclaim bag" (which, of course must be reclaimed itself :? at some point) and a small vac pump & tank isn't a big deal to me.  Those bags don't last forever and they ain't cheap, either.

Also interesting to note that Whirlpool says you don't even need the gauge set, though I would never work on a sealed system without a gauge set to watch pressures on start-up.



____________________
Alfred