Moisture and Carbon Monoxide

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Yeah, right, you got me, I'm a newbie in this trade.
Do I get a star for knowing more than you in such a short time?
It's pretty bad to get your horns clipped by a newbie Eh, Bob?
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Just curious, on a cold day when the system has been idle for days, what's the pressure inside the system?
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What's the temp, and what's the refrigerant?
LLoyd
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Lloyd E. Sponenburgh wrote:

The discussion started with Puron 410a; ambient temp whatever, say 40F
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"Whatever" isn't an exact enough temperature to look up on a pressure graph. 40F is.
My point wasn't to quote the pressure to you, but to say that the answer depended upon those two variables ... and at least one other; that being whether or not there's enough gas in the system for it to be at equilibrium between gas and liquid phases. If the latter is met, then one can determine what the pressure will be. If not, some of the experts here might do it, but I couldn't.
I should've been less cryptic, and just said, "It depends upon the refrigerant and the temperature."
LLoyd
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Bennett Price wrote:

What do you want it to be?
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Is it higher or lower than atmospheric?
Tekkie wrote:

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Your supposed to start with "Is it animal, mineral, or vegatable??"

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Bennett Price wrote:

Hey you fundie top poster...
Yes it is!
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I really didn't know the best place to enter this discussion, so I fiquired the top would be best.
Long but interesting.
First, I had heard this before and thought this 'asperation of moisture' effect was happening at a K-Mart cafeteria.
1970's At K-Mart I came upon the job where the See All was bright yellow. Original complaint, cooler would warm up and then cool down. Easy fix, moisture plugging up the TXV; changed the dryer out and came back in 24 hours for another check and change out of the drier one more time. This is before the new EPA laws and we never heard of a recovery machine back then. Next day all is well, changed the dryer again and the unit worked for about four months and the same problem came back. . Changed the dryer again and tested for more leaks, zero leaks, nothing, system ran for another four months then pure yellow again. The system was 502 inside so it never pumped into a vacuum.
Well, I was talking to a real old timer at an RSES meeting and asked him about this and his reply really surprised me. He said they never had that problem with the belt drive units unless the seal leaked, but with these 'new fangled sealed compressors" he's seen it more than he wanted to.
Remember, in the 70's their were a lot of belt drives, moisture was a big problem for wax and icing the TXV, but the electrical motor was not in contact with the electrical fields, you changed the driers as many times as you needed since driers were cheap. The old belt drive units even had a bleeder valve on the top of the condensers so you could purge off the non condensables. He stated that belt drives units didn't need that great of an evacuation since the motor isn't in the refrigerant, we had no 'burnt' refrigerant back then. There was acid etc but no burn outs 'inside' the refrigerant portion since the motor was outside the sealed system. He then said the new 'hermetics' had open windings where the refrigerant passed over, and when non condensables cross over a hermetic compressors windings and it goes over the electrical fields it breaks down or separates the refrigerant from the non condensables and somehow plays with the chemistry and the oxygen and hydrogen do something and you get moisture. So, I blew the charge, evacuated over night with an old Robinair micron indicator to very low microns, charged the unit, and this never happened again.
Believe what you want concerning this, I know it goes against the grain and I'm not a chemist, all I know is in the next seven years they operated that restaurant we never had this problem come back.
As to moisture getting into the system with a higher pressure than atmosphere I have heard this before, it has to do with one of the laws, (not boyles) but another, which I just can't remember at the time. I thought that was happening with this K-Mart job, but I think the old man may have been correct. Remember, the newest versions of compressors were different back in the 70's. lots of open windings compared to today.
Rich
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Very interesting and informative disscussion here- thanks to all. I also had never heard about this, even in the 410 classes I have been to. In the case of Geoman's KMart cooler, I am wondering if somehow it got water in the system and it found it's way to the bottom of the compressor and stayed there under the oil, effectively sealed from the rest of the sysem-- and the vac pump- for a while until heat, vibration and circulation of the oil released enough to cause freezing at the TXV. Then the free moisture was removed by the new drier, so the unit worked ok for a while until more was released. Just a thought. Larry
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Nice read. Thanks for sharing.
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Larry's got the best answer. I've read in my SAM's manuals [RSES Service Application Manuals] about oil harboring moisture [even at 1,000 microns the oil 'may' still contain moisture under it.]
Remember though, we have better vacuum pumps today, and micron gauges. Back in the 'good ole days' they only had mercury manometer's.
I believe the only way moisture could get into a 'sealed refrigeration system' is by a careless technician with bad habits, or faulty braze joints with fittings not completely filled in with braze material. [I've seen cut-a-ways where moisture can hide inside the wall of a poorly brazed fitting.]
--
Zyp

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Zephyr,
Agreed that moisture can be in oil at 100 microns, but back then we only had mineral oil, and one 162 drier cleaned the moisture indicator up and then I changed it again. I don't believe they would have cleared up after one drier change out if there was that much moisture. This is the reason I give that old man some credibility. I'm not denying that its hard to believe, I'm not quite sure what to believe about this.... The system only had like 7 pounds of gas in it, I changed the dryer because it was the fastest way to get them cooling and I fiquired we could work on it later when the box turned down in temp. But the driers did their job for four months.
Oh, btw, mercury manometers are better than electronic instruments if I'm not mistaken, and yes, we do have better pumps.

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