So; I ordered some of this gas. It interests me because it's not a phase-out refrigerant; and can be purchased over-the-counter in small cans. I feel as if this experimentation will benefit hobbyists as well as professionals who choose to work on antiques but don't do so often. It should help those who do not have a license; or who are licensed but don't want to purchase a large container of something which may not get used often. Note that this is different from R1234YF, which is the current automotive refrigerant. Further note that absolutely no discussion about environmental politics is welcome in this thread.
We have determined that R152A works well in most old refrigerators. It increases the capacity when compared to SO2, which places more load on the compressor. If the system is operated within reasonable ambient temperatures and has an adequate design, this is not a problem. There are certain designs which seem to suffer more with this added capacity. For this reason I believe that investigation is wise, of new gases which become available.
The biggest problem facing use of R152A in place of SO2 has been, (in my experience and talking with others), improper operation of float valve metering systems. The density of R152A is far less that of SO2. This causes a change in float level, or a failure of the float to lift at all. Certain systems are relatively easy to modify to work perfectly with the lighter refrigerant, however others are not able to be modified within reason.
The HFO-1234ZE(E) falls between R152A and SO2; both in density and pressure - temperature curve.
Liquid Densities at 10F (kg/m3) Comparison to SO2
R124 1474.3 + 0.5%
SO2 1467.3
R134a 1334.1 - 9 %
R1234ZE 1293 -13% (note - temperature not specified in chart)
R152A 986.1 - 33 %
Looking at this information above, I would expect that most high-side float systems designed for SO2 would still function with 13% less dense R1234ZE. We know that the 33% less dense R152A liquid will "usually" work in all but the most demanding systems.
The temperature - pressure characteristics are also closer to the original design SO2. I chose condenser temperatures to compare, because that is what seems to make the most difference to the stress on the machine.
At 40C (104F)
R152A - 129 PSIA
R1234ZE - 111 PSIA
SO2 -87 PSIA
So as you can see, there will be a capacity increase; but not as profound as the increase from SO2 to R152A. Since most of the SO2 antiques have plenty of excess power; this will be a side-benefit. It could be a real benefit for the low HP early Frigidaire Meter-Miser R114 systems.
Gas density is another interesting property. I'm not sure how much change in machine stress level it will provide. If I am not mistaken, it makes a real difference in sound waves traveling in the gas. We know that the very dense refrigerants change the sound of the machine. My hearing is poor but it seems that the heavier gases give a more "rich and smooth" sound whereas SO2 tends to be more tinny and crackly.
Gas densities at 10F:
Refrigerant Density (kg/m3) Comparison to SO2
R134a 9.23 + 332 %
R124 6.59 + 237 %
R1234ZE 5.71 + 205% (note - temperature not specified in chart)
R152a 5.39 + 194 %
SO2 2.78
Of course all of this is just theorization and conjecture at this point. If anyone has more info, better math, easier tables to read - by all means please share!
[UPDATE] Received the gas.
Finally got an update with this refrigerant! Life got in the way and I only just now got around to putting it in the Frigidaire.
As you may remember - this one had broken terminal seal and leaked out its oil and original R114 charge. I have been running it with R152A, which worked well. It did, however, put more load on the compressor. The rated running current is 1.9 - 2.1 amps; and the unit required 2.16 amps under stable running conditions with the R152A. I would expect it would have run for years like this, but none the less, it was a good candidate for this experiment.
The picture shows the low-side gauge running in a vacuum of about 10"Hg. It further pulled down to 11"Hg after the cabinet cooled off. The motor current was around 1.99 amps, in a very warm environment.
The cans of R1234ZE are about 4 times the cost of R152A, so this would be something to use only when the system fails to work with anything else. But I expect the price will come down.
Video of charging: youtu.be/to99qC6pafU
We have determined that R152A works well in most old refrigerators. It increases the capacity when compared to SO2, which places more load on the compressor. If the system is operated within reasonable ambient temperatures and has an adequate design, this is not a problem. There are certain designs which seem to suffer more with this added capacity. For this reason I believe that investigation is wise, of new gases which become available.
The biggest problem facing use of R152A in place of SO2 has been, (in my experience and talking with others), improper operation of float valve metering systems. The density of R152A is far less that of SO2. This causes a change in float level, or a failure of the float to lift at all. Certain systems are relatively easy to modify to work perfectly with the lighter refrigerant, however others are not able to be modified within reason.
The HFO-1234ZE(E) falls between R152A and SO2; both in density and pressure - temperature curve.
Liquid Densities at 10F (kg/m3) Comparison to SO2
R124 1474.3 + 0.5%
SO2 1467.3
R134a 1334.1 - 9 %
R1234ZE 1293 -13% (note - temperature not specified in chart)
R152A 986.1 - 33 %
Looking at this information above, I would expect that most high-side float systems designed for SO2 would still function with 13% less dense R1234ZE. We know that the 33% less dense R152A liquid will "usually" work in all but the most demanding systems.
The temperature - pressure characteristics are also closer to the original design SO2. I chose condenser temperatures to compare, because that is what seems to make the most difference to the stress on the machine.
At 40C (104F)
R152A - 129 PSIA
R1234ZE - 111 PSIA
SO2 -87 PSIA
So as you can see, there will be a capacity increase; but not as profound as the increase from SO2 to R152A. Since most of the SO2 antiques have plenty of excess power; this will be a side-benefit. It could be a real benefit for the low HP early Frigidaire Meter-Miser R114 systems.
Gas density is another interesting property. I'm not sure how much change in machine stress level it will provide. If I am not mistaken, it makes a real difference in sound waves traveling in the gas. We know that the very dense refrigerants change the sound of the machine. My hearing is poor but it seems that the heavier gases give a more "rich and smooth" sound whereas SO2 tends to be more tinny and crackly.
Gas densities at 10F:
Refrigerant Density (kg/m3) Comparison to SO2
R134a 9.23 + 332 %
R124 6.59 + 237 %
R1234ZE 5.71 + 205% (note - temperature not specified in chart)
R152a 5.39 + 194 %
SO2 2.78
Of course all of this is just theorization and conjecture at this point. If anyone has more info, better math, easier tables to read - by all means please share!
[UPDATE] Received the gas.
Finally got an update with this refrigerant! Life got in the way and I only just now got around to putting it in the Frigidaire.
As you may remember - this one had broken terminal seal and leaked out its oil and original R114 charge. I have been running it with R152A, which worked well. It did, however, put more load on the compressor. The rated running current is 1.9 - 2.1 amps; and the unit required 2.16 amps under stable running conditions with the R152A. I would expect it would have run for years like this, but none the less, it was a good candidate for this experiment.
The picture shows the low-side gauge running in a vacuum of about 10"Hg. It further pulled down to 11"Hg after the cabinet cooled off. The motor current was around 1.99 amps, in a very warm environment.
The cans of R1234ZE are about 4 times the cost of R152A, so this would be something to use only when the system fails to work with anything else. But I expect the price will come down.
Video of charging: youtu.be/to99qC6pafU
