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Post by cablehack on Jan 4, 2015 0:51:17 GMT
What about the worn compressor though? Won't a stronger compressor cause issues with the same cap tube? Similar to cablehack's 50Hz vs 60Hz? Interesting point. I wonder if a leaky-past-the-seals/valves compressor is the same as a reduction in horsepower. I would think that a lower horsepower compressor can get to a certain vacuum but just take longer, but a worn one could never achieve it. But if I ever did put R123 in a CA, John's cap tube calculation would have to be changed in my instance because of lower rpm. I think from memory about 1.4 times longer would be my starting point. |
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Post by blackhorse on Jan 4, 2015 5:05:02 GMT
The stated reason for adopting 60Hz given was that early on at 50 Hz the flicker was annoying in office lighting.
Do you notice flicker, or is there some provision in Aus to minimize it?
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Post by jhigdon2 on Jan 4, 2015 18:55:19 GMT
Yes. I'm sure that a slight cap tube adjustment would probably be needed if the compressor was in good shape. The saving grace with using the R123 is that is has a slightly more aggressive low temp curve than methyl formate. So having a worn compressor isn't a big deal, since it only has to have evap temp in the low single digits for this application. However I have noticed something interesting. It seems that the compressor performance is slowly improving this last week. It now will easily bring the evap temp down to a few degrees below zero if I turn the thermostat colder. So maybe there is hope for this worn old pump yet. In conclusion I see R123 as a perfectly viable modern refrigerant alternative to methyl formate. The unit is just as quiet, if not quieter than a methyl formate unit.
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Post by cablehack on Jan 4, 2015 22:50:53 GMT
The stated reason for adopting 60Hz given was that early on at 50 Hz the flicker was annoying in office lighting. Do you notice flicker, or is there some provision in Aus to minimize it? That's the most bizarre reason I've heard yet. Mains frequencies were determined well before fluorescent lighting existed (ca. 1939). Incandescent lamps, especially carbon filament ones used in the early 20th century have such a high thermal inertia that flicker is a non issue (25c/s was used in parts of Canada, 40c/s in one Australian state, amongst other places). 50c/s was chosen by the German companies like AEG and Siemens who built a lot of Europe's generating equipment. This influenced the UK and thus Australia. My understanding is 50c/s was chosen because it fits in with the metric system. 60c/s does have the advantage of requiring less iron in transformers and motors, and I believe that 60 was chosen rather than some other random number because of its association with time; i.e. 60 seconds in a minute, etc. No, there is no obvious flicker from fluorescent lighting except with an old tube nearing the end of its life, and then only if you look directly at the tube. |
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Post by cablehack on Jan 4, 2015 23:01:01 GMT
It seems that the compressor performance is slowly improving this last week. That sounds like something had deposited itself on the compressor surfaces over the time it wasn't being used and is now being washed off. |
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Post by ChrisJ on Jan 5, 2015 0:35:35 GMT
Or, is copper plating taking place for some mysterious reason?
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Post by cablehack on Jan 5, 2015 2:57:35 GMT
Or, is copper plating taking place for some mysterious reason? I remember reading somewhere about R123 reacting with something and it reduced my enthusiasm for actually pursuing the idea for my CA-2. I think it must have been moisture content or something like that - knowing it was contaminated. Something about motor windings bothered me but I can't remember now. For my CA-2, I came to the conclusion R601a would be a more suitable modern refrigerant given that moisture is less problematic with hydrocarbons. |
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Post by blackhorse on Jan 5, 2015 5:23:24 GMT
That's the most bizarre reason I've heard yet. Mains frequencies were determined well before fluorescent lighting existed (ca. 1939). Incandescent lamps, especially carbon filament ones used in the early 20th century have such a high thermal inertia that flicker is a non issue (25c/s was used in parts of Canada, 40c/s in one Australian state, amongst other places). 50c/s was chosen by the German companies like AEG and Siemens who built a lot of Europe's generating equipment. This influenced the UK and thus Australia. My understanding is 50c/s was chosen because it fits in with the metric system. 60c/s does have the advantage of requiring less iron in transformers and motors, and I believe that 60 was chosen rather than some other random number because of its association with time; i.e. 60 seconds in a minute, etc. No, there is no obvious flicker from fluorescent lighting except with an old tube nearing the end of its life, and then only if you look directly at the tube. I believe they were referring to arc lights. The discussion I recall goes back to the old General Electric vs Westinghouse competition at the turn of the (last) century. Attachments:60Hz.tiff (487.58 KB)
60Hz 2.tiff (698.57 KB)
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Post by ChrisJ on Jan 5, 2015 7:08:50 GMT
That's the most bizarre reason I've heard yet. Mains frequencies were determined well before fluorescent lighting existed (ca. 1939). Incandescent lamps, especially carbon filament ones used in the early 20th century have such a high thermal inertia that flicker is a non issue (25c/s was used in parts of Canada, 40c/s in one Australian state, amongst other places). 50c/s was chosen by the German companies like AEG and Siemens who built a lot of Europe's generating equipment. This influenced the UK and thus Australia. My understanding is 50c/s was chosen because it fits in with the metric system. 60c/s does have the advantage of requiring less iron in transformers and motors, and I believe that 60 was chosen rather than some other random number because of its association with time; i.e. 60 seconds in a minute, etc. No, there is no obvious flicker from fluorescent lighting except with an old tube nearing the end of its life, and then only if you look directly at the tube. I believe they were referring to arc lights. The discussion I recall goes back to the old General Electric vs Westinghouse competition at the turn of the (last) century. In the 1890s a local factory a block from our house was using "Rochester lamps" according to a fire insurance map I have. Was something I had never heard of and it blew my mind when I found out what it was. I'd love to see one in action. They also appear to have been called center draft oil lamps. They use a cylindrical wick and are far brighter and whiter than a normal oil lamp. youtu.be/lb4JM3xUdJU |
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Post by cablehack on Jan 6, 2015 22:14:28 GMT
I believe they were referring to arc lights. The discussion I recall goes back to the old General Electric vs Westinghouse competition at the turn of the (last) century. Interesting articles, and much as I expected with the exception of the bit about arc lights. I can see the problem with arc lights is the asymmetric current draw depending on polarity. Thus, a more pronounced 60 or 50Hz flicker rather than 120 or 100 with incandescent lamps. Interesting to see GE liked 50Hz  |
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Post by birkie on May 28, 2017 18:01:48 GMT
Resurrecting an old (and fascinating!) thread, I did a few theoretical calculations on R123 in a CA. In an ideal system with an evaporator saturation temperature of 15F, and a condenser temperature of 100F, R123 would have
- more head pressure (110%) than methyl formate
- lots more mass flow (329%)
- higher capacity (121%)
For cablehack's CA, it looks like the 21% increase in capacity would make his 50Hz machine on R123 almost perfectly match a 60Hz machine on methyl formate!
I'm pretty sure the worn out compressor on this guinea pig is what made it perform as "normally" as it did, all things considered. The de-tuning must have been a decent match to she slightly more aggressive R123.
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