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Post by jhigdon2 on Aug 10, 2014 19:56:38 GMT
Well as some of you may know, I rebuilt a DR1 compressor two or three years back and the windings failed. Since then I have learned about the material incompatibility problems with S02 and modern polyamide imide windings. I decided to cut it open again and have a close look. I have asked Chris to help me with posting the pics so, it will better illustrate the chemical incompatibility issues. I am going to send the stator out for a fresh rewind this week and disassemble and clean the rest of the compressor while Im waiting for it to return. This compressor will be converted to R134 refrigerant using modifications with recent info I have learned. |
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Post by ChrisJ on Aug 10, 2014 21:55:28 GMT
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Post by ChrisJ on Aug 10, 2014 21:58:40 GMT
The Dwyer instrument has me curious. I started using a Dwyer pressure switch on my steam boiler as someone had recommended them for a cheap reliable solution. I have two of them, one that maxes out at 2 ounces and the one I'm using is set to trip at 4 ounces. The Dwyer switch is the gold colored thing in this picture. Attachments:
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Post by jhigdon2 on Aug 10, 2014 23:25:24 GMT
The picture with the flow meter in it is measuring the sq.cubic ft per hour of this panasonic 495 btu compressor. I wanted to establish a baseline scfh pumping ability for a modern R134 compressor. Then I measured the flow rate of the 350 btu DR 1 compressor. After crunching a few numbers, I have determined that the DR compressor needs detuned by about 25%. From about 24 sq. Cu ft per hr down to 17. The interesting thing I have discovered is that a length of 5/32" tubing will do the job. Not just a few inches as was suggested in a book. (Can't remember the name of the book now). It will take approx 20" inches to make the necessary change in flow to make the little DR 1 work well with R134 and keep the run amps in check.
I will see for sure if this idea works when I get it back together.
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Post by jhigdon2 on Aug 10, 2014 23:32:11 GMT
In the pictures of the bad windings you may be able to see the incompatibility issue by looking very close to the winding insulation itself. The swelled wrinkled appearance is the result of an inability of S02 to get along with the polyimide ammide. The insulation has the feel and appearance of one of those expandable garden hoses.
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Post by coldspaces on Aug 11, 2014 3:49:31 GMT
The picture with the flow meter in it is measuring the sq.cubic ft per hour of this panasonic 495 btu compressor. I wanted to establish a baseline scfh pumping ability for a modern R134 compressor. Then I measured the flow rate of the 350 btu DR 1 compressor. After crunching a few numbers, I have determined that the DR compressor needs detuned by about 25%. From about 24 sq. Cu ft per hr down to 17. The interesting thing I have discovered is that a length of 5/32" tubing will do the job. Not just a few inches as was suggested in a book. (Can't remember the name of the book now). It will take approx 20" inches to make the necessary change in flow to make the little DR 1 work well with R134 and keep the run amps in check. I will see for sure if this idea works when I get it back together. Great info!! If this works out as planned it will help in determining what I need for a restrictor in Travis's DR3. Still hoping to hide a long one in the compressor base. One length if 5/32" tube will be good for oil return. I worry that if I use a lager tube with a short restrictor and coil it mostly flat under the compressor base velocity might not be right for oil return. Great work John, thanks for posting! |
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Post by jhigdon2 on Aug 11, 2014 4:46:08 GMT
S02 is much has much less density than R134. My theory is that the design of the S02 compressor is just way to volumetric efficient for R134 and must be choked down a bit on the intake, so that it's not taking such big bites. It is also Interesting that whenever I have tried R134 in one of these monitor top compressors, the run amps and overall power consumption is about 25% high also. Hmmm. Kinda got me to thinking. So I decided to make a flow comparison. I tried several different lengths of tubing and found out that it takes alot longer length of restriction than I expected.
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Post by ChrisJ on Aug 11, 2014 11:11:39 GMT
Would a bypass be of any use? Perhaps a piece of cap tube brazed in between the suction and liquid line?
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Post by jhigdon2 on Aug 11, 2014 16:04:18 GMT
A person probably could achieve the same results that way, but the bypass would tend to equalize the high and low side of the system during off cycle. I would think this would behave much the same as a leaking check valve and the results would be short off times.
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