Exploring R-30 as an alternative refrigerant for the CA...
Mar 7, 2023 14:57:36 GMT
cablehack, ckfan, and 2 more like this
Post by turbokinetic on Mar 7, 2023 14:57:36 GMT
It's been two years now, so I feel confident enough to share this openly with the group. There are quite a few threads on here about conserving and obtaining methyl formate for these refrigerators. It has been a problem for a long time because there is only one supplier and they are very difficult to deal with and seem to pick and choose who they sell to with no particular rhyme or reason.
Due to the boiling point and therefore temperature / pressure chart for methyl formate, there are few refrigerants which can replace it. Freon-11 and R-123 were the first replacements, but those have both been phased out now. Beware the R-11 "flushing solvent use only" cylinders you find from time to time. Trust me you have been warned. These contain noncondensable propellants to drive this product out of the container for flushing.
In my studies of the early refrigeration systems, dichloromethane / methylene chloride was another vacuum refrigerant. Grunow called it Carrene. The industry gave it the R number R-30. This has uses for cleaning as well as an ingredient in other products. The reason this was a good choice to investigate is because it is available in small containers and not overly expensive.
I took a CA machine which was just about ready for the scrapyard, and decided it was going to be the test case. This machine had a very hard time starting due to some form of wear in the mechanism. As said, nothing to lose.
The literature from Grunow stated that they used an oversize drier to protect against corrosion. I mention that in the video, but after this video was made, I found additional information that this may not be the case and that moisture alone would not cause problems unless combined with a source of oxygen; which seems to be the case with all chlorinated refrigerants including R12. So there is that and I may try another test case without an additional drier.
One concern with the CA and a drier is the low operating pressure, and the pressure drop caused by the drier. There isn't a lot of head-room for additional pressure drops in the system. I settled upon a suction line drier for the experimental unit, since that would be the least likely to provoke refrigerant to condense in the compressor housing, versus a drier before the float chamber.
The following videos document this project, and its follow up. Over the last two years it has been in continuous operation without any problems.
Note well, I have to say that it is only two years into a test of a machine which can operate for many decades, so it's still a very short test at this point. Your mileage may vary and I am not saying this is a universal methyl formate replacement for everyone to start using with reckless abandon. I am just saying that mine is still working after 2 years; and the machine seems to be mechanically improving with time. The next one will be done without a drier, as another test case to see if R-30 can be used as a refrigerant in a totally unmodified CA machine.
Due to the boiling point and therefore temperature / pressure chart for methyl formate, there are few refrigerants which can replace it. Freon-11 and R-123 were the first replacements, but those have both been phased out now. Beware the R-11 "flushing solvent use only" cylinders you find from time to time. Trust me you have been warned. These contain noncondensable propellants to drive this product out of the container for flushing.
In my studies of the early refrigeration systems, dichloromethane / methylene chloride was another vacuum refrigerant. Grunow called it Carrene. The industry gave it the R number R-30. This has uses for cleaning as well as an ingredient in other products. The reason this was a good choice to investigate is because it is available in small containers and not overly expensive.
I took a CA machine which was just about ready for the scrapyard, and decided it was going to be the test case. This machine had a very hard time starting due to some form of wear in the mechanism. As said, nothing to lose.
The literature from Grunow stated that they used an oversize drier to protect against corrosion. I mention that in the video, but after this video was made, I found additional information that this may not be the case and that moisture alone would not cause problems unless combined with a source of oxygen; which seems to be the case with all chlorinated refrigerants including R12. So there is that and I may try another test case without an additional drier.
One concern with the CA and a drier is the low operating pressure, and the pressure drop caused by the drier. There isn't a lot of head-room for additional pressure drops in the system. I settled upon a suction line drier for the experimental unit, since that would be the least likely to provoke refrigerant to condense in the compressor housing, versus a drier before the float chamber.
The following videos document this project, and its follow up. Over the last two years it has been in continuous operation without any problems.
Note well, I have to say that it is only two years into a test of a machine which can operate for many decades, so it's still a very short test at this point. Your mileage may vary and I am not saying this is a universal methyl formate replacement for everyone to start using with reckless abandon. I am just saying that mine is still working after 2 years; and the machine seems to be mechanically improving with time. The next one will be done without a drier, as another test case to see if R-30 can be used as a refrigerant in a totally unmodified CA machine.
https://youtu.be/QOd7fQOUCeMhttps://youtu.be/n9KK_mXz-qMhttps://youtu.be/RxGtntShE2M
