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Post by turbokinetic on Jun 22, 2018 13:00:44 GMT
Thanks for the link to Leak Lock. That looks like a great product for this application. It seems to be holding well now, but if I have to open it up again, I will definitely give that a try.
Outstanding progress! Just thinking about the control. The fact that it uses the low-side pressure presents an interesting twist when using different refrigerants. So here are some pressures at a saturation temp of 10F: Refrigerant | psia | gague pressure | Absolute pressure from SO2 | SO2 | 13.3 | 2.7" vacuum | - | R124 | 14.5 | 0.3" vacuum | +9% | R134a | 26.62 | 11.9 | +100% | R236FA | 9.19 | 11.2" vacuum | -31% |
So I'm not entirely sure how to analyze this yet. R124 is pretty close - I'd be fairly confident that some minor adjustments would make it work. The R134a would need 2x the force opposing it for a given temp than the SO2. Atmosphere provides some of that, and various springs in the control provide the balance. The "bias" needed in order to balance out the additional 11.9 psi from R134a may be significant. It's hard to visualize in my head - but that control looks like it has so many different parameters that can be tweaked. I'm optimistic you'll find a way one way or another. I think the bias difference from the 11.9 PSI could be figured by taking the surface area of the bellows, the differential pressure between atmospheric and SO2 pressure; and then doing the same for R134A pressure. That would give the actual force developed by each, at the bellows. Then measurements of the lever length and fulcrum point could scale these force calculations to what the main spring would need to provide to keep it in balance. Or, pump the control up with air and a calibrated gauge and make experimental adjustments LOL! Definitely it does make it more interesting and challenging! It's a compromise between liquid density (for the low-side float), temperature/pressure curve, and oil miscibility. Very much will be learned I'm sure LOL. I'm reasonably sure that the control can be calibrated to work with a higher pressure refrigerant. It seems that the main spring (large one to the left of the center of the control) could be adjusted to get it in the range where it needs to be; allowing the others to do their job with finer adjustments. I'm still searching for R124 locally, but as said before it seems that there is none around. I did have someone acknowledge that they used to have it for a local hospital; but haven't sold any in years. He also told me there was a "refrigerant buy-back" representative who made the rounds in this area recently and all the low volume sellers have been sent off already. Probably will turn up on eBay at ridiculously inflated prices in the upcoming years.
I’m just blown away. This is beyond cool! I really like what you did to save the motor. I can’t believe it didn’t have an internal fan either. That should help the old windings hold up better. The supco 3 in 1 is a good idea since you didn’t have the parts for the start circuit. I’m also glad that the compressor seems to be holding pressure just fine. Thanks for leaving the bright work unpainted. Kind of reminds me of old engines from the turn of the last century which had all kinds of brass, copper, and nickel. Glad you appreciate it! Agreed that i's worth the time to keep the "bright work" looking "bright" so to speak! The service valves were in amazing shape with all I did being washing them with degreaser and hot water.
Along this line, I plan to install a hidden strip of LED lights in the lower compartment, along the inside surface of the front upper wooden frame of the compressor compartment. It will shine down and back from above the compressor skid. It should be concealed where you can't see the light source, but will allow seeing the compressor skid even though it would be shadowed badly otherwise. Just a thought.
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Post by turbokinetic on Jun 23, 2018 1:49:58 GMT
Got some more progress made today! Actually, the compressor skid is finished!
The new belt is on. It was available at Advance Auto Parts.
That looks like it belongs there. Runs completely true and quietly as well.
The compressor skid had metal flex conduit on it for the motor wiring. It was a little short and they had exposed wires from the end of the flex going to the motor. I know that wouldn't have been how the factory would have done it, so I replaced that flex with a new, longer piece. Also, mine has a ground conductor.
Fuseholder in place. Had to do some soldering and repairing to the contacts. It has had a long, hard life.
Wiring complete, with new cloth covered 3-wire grounded cord. This is the compressor skid, finished!
(continued)
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Post by elec573 on Jun 23, 2018 2:35:59 GMT
Very nice, looking forward to seeing and hearing this one run.
Like the the idea of the LED lights even though it’s not time period.
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Post by ckfan on Jun 23, 2018 13:03:03 GMT
That’s so cool that you were able to make it cool that oil cooler down. Very neat! I’m very hopeful that you will be able to make it work. It obviously pushes out quite a bit of oil!
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Post by turbokinetic on Jun 23, 2018 14:48:01 GMT
Very nice, looking forward to seeing and hearing this one run. Like the the idea of the LED lights even though it’s not time period. Thanks! For the LED lights, I'm hoping for something that can't be seen from any normal angle a person might try to look at the unit. It's just a thought! Thankfully the video finally uploaded, as well, so seeing an hearing it run can be arranged LOL!
That’s so cool that you were able to make it cool that oil cooler down. Very neat! I’m very hopeful that you will be able to make it work. It obviously pushes out quite a bit of oil!
Thanks! I just couldn't resist the urge to make a function test! It does pump a lot of oil. That is for sealing around the pistons (remember there are no piston rings!) as well as keeping the reed valves clean and lubricated. Maybe they also hoped it would preserve the float valve functionality, as well? I believe the GE Scotch Yoke compressors use a similar sealing method with an oil groove around the circumference of the cylinder.
I did finally get the pictures up!
The cover in place over the control contacts:
Wiring job complete! I like the way that metal clad flex looks.
The spring in my hand is the original one from the control. The blue one in place now is from a transmission valve body. It is stronger, and allows for cycling in the 5 to 20 PSI range.
Function testing with car engine oil cooler for stand-in evaporator. Gauges are being used as a manual metering device.
Got frost all over the coils!
So that's how she sits at the moment! Next will be when I have the cabinet home and can start assembly.
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Post by birkie on Jun 23, 2018 15:57:59 GMT
Very nice - it lives! That sure was fast - you shaped metal and adapted parts as if it was nohhing. it makes it look easy, but there's a lot of work in that now-functional compressor. Way to go The spring in my hand is the original one from the control. The blue one in place now is from a transmission valve body. It is stronger, and allows for cycling in the 5 to 20 PSI range. That's very promising. While watching the video, it dawned on me that controlling the pressure with the valve of the gauge set (as you were doing) would be a great way to vary the pressure of the low-side so that you can observe when it trips on and off. That's pretty clever. Is that what you did in order to ascertain that the transmission valve body spring gets you in the right ballpark?
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Post by turbokinetic on Jun 23, 2018 16:23:39 GMT
Very nice - it lives! That sure was fast - you shaped metal and adapted parts as if it was nohhing. it makes it look easy, but there's a lot of work in that now-functional compressor. Way to go Thanks again for the compliments! It was a lot of work, but I enjoy these sort of challenges. It's fun to see potential in something which, to others, is a mere relic to be looked at. I want to be able not only to SEE it; but to feel it and hear it and have it be a living piece of history, so to speak. The spring in my hand is the original one from the control. The blue one in place now is from a transmission valve body. It is stronger, and allows for cycling in the 5 to 20 PSI range. That's very promising. While watching the video, it dawned on me that controlling the pressure with the valve of the gauge set (as you were doing) would be a great way to vary the pressure of the low-side so that you can observe when it trips on and off. That's pretty clever. Is that what you did in order to ascertain that the transmission valve body spring gets you in the right ballpark?
Yep it is promising! When experimenting with the control, I had a pressure source, gauges, and just the control connected. With that, I could easily and gradually change the pressure in the control bellows. It was then just a matter of trying a few different springs until this one was found. It allowed operation "in the ballpark" where I wanted it, with the other adjustments sort of in a midrange position. That way I have room to tweak it either way as necessary once the unit is running.
That is actually a left over part of a TransGo SK440JR kit LOL!
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Post by icebox on Jun 23, 2018 21:36:27 GMT
Great work. Love the video - I can't believe how quiet it sounds. If I hadn't seen the photos of it when you picked it up I could believe it was new - such a good restoration.
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Post by turbokinetic on Jun 23, 2018 21:42:46 GMT
Great work. Love the video - I can't believe how quiet it sounds. If I hadn't seen the photos of it when you picked it up I could believe it was new - such a good restoration.
Thanks! I really appreciate this. This is a problem, though! It looks "new" and not "antique" LOL! It was too far gone to try to save the patina, and besides, this sort of machinery needs to be perfectly clean and leak-free. There was just no way around a full teardown and refurbish.
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Post by solarmike on Jun 24, 2018 2:52:42 GMT
Man you do some of the nicest work that I have seen on here..... Thanks for sharing...
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Post by elec573 on Jun 24, 2018 2:56:10 GMT
Agree on full tear down and rebuild. Something that old , needs a good cleaning and repairing where needed ! Very well done it looks new and is quite. And you did it very quickly I’m impressed !
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Post by turbokinetic on Jun 24, 2018 14:21:51 GMT
Man you do some of the nicest work that I have seen on here..... Thanks for sharing... You're very welcome; I appreciate your compliment greatly! It's really satisfying to get things like this working again. I enjoy doing it as well as sharing it. Agree on full tear down and rebuild. Something that old , needs a good cleaning and repairing where needed ! Very well done it looks new and is quite. And you did it very quickly I’m impressed ! Definitely needed a good cleaning! I was most concerned about internal corrosion after the SO2 leaked out and air got back in the system. I knew it was now or never for this compressor; as well as the receiver tank. If that got all corroded internally, it would be impossible to clean it out. Now it has no SO2 residue, fresh oil, and a noncorrosive gas in it. So I can sleep at night LOL! It seems that Frigidaire engineering went to great lengths to make this machine quiet for in-home use. There are many layers of rubber isolators. The motor sits on them, and then the entire skid hangs from springs, sitting on rubbers. It seems this is likely one of the last domestic open-drive designs before the hermetic motors came onto the scene. They had evolved it pretty well by now it seems. I had contemplated washing out the compressor with new oil and letting it go. But, I decided against that. A person can get away with a little more "let it be" attitude when restoring antique fans or motors or the like. But, with a refrigerant system, it doesn't matter old or new there's just no way around a clean and leak-free system. As we all know, the industry has evolved to minimize and remove joints, gaskets, fittings, and the like so that the systems are less likely to leak. This one has numerous potential leak points. Time will tell how it holds refrigerant! At least now it won't be sulfur dioxide that would leak if it leaks!
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Post by turbokinetic on Jun 25, 2018 2:27:05 GMT
Got a little float valve re-visit today!
As most of us know; the job of the needle valve is to restrict the incoming flow of liquid refrigerant as the flooded evaporator fills with liquid. The float bulb rides up on the rising liquid and the linkage moves the needle closed. This is what regulates the system, instead of an expansion valve or capillary tube.
If the float does not rise, the evaporator will fill with liquid up to the suction line area. This will allow liquid floodback to the compressor. That would be bad for the compressor and reduce the cooling of the unit, since the liquid would boil violently in the hot compressor sump and raise the low side pressure.
The float was made for SO2 refrigerant liquid. This is a very dense liquid, 1467 kg/m3 according to what Aaron posted earlier (thank you!). I want to use something other than exotic refrigerant such as SO2, or even R124 because I can't get it locally. The next logical choice is R134A, with only a 9% difference in liquid density. I have been pondering how to test the float off-system and ensure it is calibrated to work. Then I noticed the density chart showed R152A with a density of 986 kg/m3. That is so very close to 1000 - the density of water. This opened up a very interesting possibility. I was able to fill up the sink with water and clamp the float assembly to a stand, in the sink. Instant function test! The results were that with water, the float would not float. It's denser than water. I expected this because the float is really heavy and made of thick brass. Not one to be deterred, I added a counterbalance spring to the mechanism, so that the float would indeed rise up on the water.
After tweaking the adjustment screw (with the spring in place) I was able to get the float to close off the needle valve just before the water level was at the return port. This shows what happens in static conditions; but things will be far from static in the operating system. The refrigerant in the evaporator will be boiling, and therefore have vapor bubbles or foam in it. That reduces the density, and would raise the level around the float before it closed off the valve. So, as an educated guess, I left the adjustment about 3/8" below the small holes in the return port; under static conditions.
The good thing about this system is that it can be "pumped down" and worked on with a full charge in place. So if it needs adjustments, I can fairly easily make them.
The level at which needle contacts seat:
Note that I need to buy a deeper sink if I continue to do these tests LOL!
Hope this is interesting to y'all. It sure is to me!
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Post by elec573 on Jun 25, 2018 5:11:44 GMT
Hay if it works don’t worry about it. It’s good thinking! We use what works.
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Post by turbokinetic on Jun 25, 2018 14:46:24 GMT
Hay if it works don’t worry about it. It’s good thinking! We use what works. Yep, you gotta find a way - I'm sure similar testing was done back in the day when this was designed!
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