Alternative to R508

[wdrzal]

R-508A, azeotropic mixture of HFC-23 and PFC-116. blend- R-23/116 (39.0/61.0)
R-508B, azeotropic mixture of HFC-23 and PFC-116. blend-R-23/116 (46.0/54.0)


400 series .... zeotropes
500 series.... azeotropes

[Shingoshi]

Man, I was thinking I'd want to use R-508a before I read all of this. And I'm guessing that because it has an even higher concentration of R-116, it's even more expensive than R-508b. As cost was likely the reason for reformulation in the first place.

So my question is whether I can use R-23 in my Rechi compressors? And I thought that if the pressure was maintained high, that R-744 would remain as a liquid and not solidify. How much pressure is required to keep R-744 as a supersaturated liquid? What parts of the system are most likely going to experience this problem?

EDIT: I was looking for a place to mention this. Were any of you aware that Sulfur Dioxide was the refrigerant of choice before Freon.

http://en.wikipedia.org/wiki/Sulfur_..._a_refrigerant
As a refrigerant

Being easily condensed and possessing a high heat of evaporation, sulfur dioxide is a candidate material for refrigerants. Prior to the development of freons, sulfur dioxide was used as a refrigerant in home refrigerators.

So how would anyone benefit now from the use of R-764 instead of R-744?

Shingoshi

[[XC] gomeler]

The capillary line. Use R-23 or R-170 over R-744. Dry ice are issues horrible.

[Shingoshi]

The capillary line. Use R-23 or R-170 over R-744. Dry ice are issues horrible.

Can I use R-23 in my Rechi compressors without any concern?

Are there any means to mitigate the icing of R-744? Seems this would be an issue of mixture, by how much is used proportionally with other refrigerants. There has to be something that can be done, or no one would ever use it. So what about my question above concerning R-764?

How can R-717/Ammonia be safely used? Same question for R-764. It seems that if the system was properly built and tested, leakage shouldn't be a factor. So just how robust would you have to build a system to eliminate the possibility of leaks?

Shingoshi

[[486]]

Can I use R-23 in my Rechi compressors without any concern?

Depends on what oil you have in them. It might not matter as PFC-116 might use the same oils as R23, or they might use different oils, and the PFC-116 in the R-508 is used as an oil carrier.

How can R-717/Ammonia be safely used?

You'll need steel pipes, ammonia is used to remove copper fouling in rifle bores, so it'll "remove" your copper pipes.

[Shingoshi]

Depends on what oil you have in them. It might not matter as PFC-116 might use the same oils as R23, or they might use different oils, and the PFC-116 in the R-508 is used as an oil carrier.

You'll need steel pipes, ammonia is used to remove copper fouling in rifle bores, so it'll "remove" your copper pipes.

1.) Is this a case where using propane would assist with the oil transfer problem? I've seen that mentioned before that using a small amount of propane can help transport oil in systems using refrigerants that weren't intended for them.

2.) Would my new brazed-plate heat-exchanger have copper in the construction?
If this thing were a woman, she'd have the biggest (.)(.) in town!

Anyone have any ideas yet on R-764/Sulfur Dioxide?

Shingoshi

[[486]]

1.) Is this a case where using propane would assist with the oil transfer problem?

2.) Would my new brazed-plate heat-exchanger have copper in the construction?
Anyone have any ideas yet on R-764/Sulfur Dioxide?

All the propane would sit condensed and not really do anything I'd guess, besides, propane and other hydrocarbon refrigerants move mineral oil well, I am pretty sure your compressor has one of the synthetic oils, but I dunno that much about your system to know for sure.

It might not, but it might, I dunno, but I do know that you do NOT wanna mess with ammonia in any system or form. I'm pretty sure the refrigeration grade is anhydrous ammonia, and that is used in drugs so you'd have a hard time getting it, and it'll mess you up REALLY bad if you breathe any in, it turns your lungs into pretty much that "astronaut ice cream" stuff.

Don't use So2 either, there is a reason we don't use it any more, it is nasty stuff too.

Just get the R-508 and consider that getting it would probably be cheaper than replacing the system if you happen to mess it up. Maybe find a guy that specializes in cascades and get him to recharge it.

[captaincascade]

In the field we isolate both the first stage side and the second stage side so that you are only pressurizing the HX itself, not the rest of the system. I install hand valves on all four lines, 1st stage in and out of HX, 2nd stage in and out of the HX. Then install 2 pressure gauges, one on the 1st stage side and one on the 2nd stage side. Pressurize one side with 200psi dry nitrogen and let sit. Come back and compare readings. If the pressurized side has fallen and the non pressurized side has risen then add both readings together and you should get 200 psi. If it dosent add up start checking for leaks in other parts of the circuit, and start the test over once they are found.

Walts (wdrzal) is the best way but is usually cost prohibative due to the cost of the test equipment. The helium molecule is much smaller than the nitrogen molecule, therefore helium can find much smaller leaks than the nitrogen test.

wow, a guy who knows what he's doing.
We could help alot more if youd post the make model and serial. I dont know if you wanna do this for your own entertainment or to save money or what, but I really think your bitting off more than you can chew especially if your gunna do some wierd exotic gas retrofit. If this is a peice of equipment used in a buisiness that is absolutely vital, you are more than likely going to do more harm than good. if you can do a majority of the labor ie; replace parts (like for like or have a proffesional help match), isure there are no leaks, and pull a good vacuum. I know my company wouldnt charge you to much to go out and chargeyour system with 508, with no waranty of course. between ultralo1 and myself we can make sure you have it right on this side.

[Shingoshi]

All the propane would sit condensed and not really do anything I'd guess, besides, propane and other hydrocarbon refrigerants move mineral oil well, I am pretty sure your compressor has one of the synthetic oils, but I dunno that much about your system to know for sure.

It might not, but it might, I dunno, but I do know that you do NOT wanna mess with ammonia in any system or form. I'm pretty sure the refrigeration grade is anhydrous ammonia, and that is used in drugs so you'd have a hard time getting it, and it'll mess you up REALLY bad if you breathe any in, it turns your lungs into pretty much that "astronaut ice cream" stuff.

Don't use So2 either, there is a reason we don't use it any more, it is nasty stuff too.

Just get the R-508 and consider that getting it would probably be cheaper than replacing the system if you happen to mess it up. Maybe find a guy that specializes in cascades and get him to recharge it.

But I've been reading that R-508 (and anything else mixed with R-116) is very expensive. If simply getting a small enough amount to charge my system is a possibility, then that might work.

How few refrigerants do you need to have an autocascade? (It's getting late, and I'm lazy. I really should be in bed by now. So I'm barely thinking.)
Wouldn't you know it? Now that I've got my Rechi compressors, the Danfoss SC18CLX.2 is available again. Maybe that'll be my fifth compressor for my second-stage.

Shingoshi

[tiborrr]

R-23 would be an only reasonable substitute for R-508B, period.
For single-stage auto-cascade you need at least two refrigerants, the so-called high temperature boiler and the low-temperature boiler. Two is - logically - the minimum

[Shingoshi]

R-23 would be an only reasonable substitute for R-508B, period.
For single-stage auto-cascade you need at least two refrigerants, the so-called high temperature boiler and the low-temperature boiler. Two is - logically - the minimum

I should have gone to bed before asking that question. That's what I thought. I was just to tired to really think it through last night.

1.) So what other refrigerants could be used with R-23 in an autocascade?
2.) Why is solidification of R-744 an issue upstream of the capillary tube?
EDIT: The above question is a mistake. I meant to ask about upstream of the expansion valve.
3.) How are people using R-744 without having the icing problem?
4.) What other refrigerants would benefit from operating at the same pressures required by R-744?

Shingoshi

[EvoCarlos]

I should have gone to bed before asking that question. That's what I thought. I was just to tired to really think it through last night.

1.) So what other refrigerants could be used with R-23 in an autocascade?
2.) Why is solidification of R-744 an issue upstream of the capillary tube?
3.) How are people using R-744 without having the icing problem?
4.) What other refrigerants would benefit from operating at the same pressures required by R-744?

Shingoshi

1. many
2.because it blocks the cap tube / evap, you should watch this vid it will expslane how co2 responds to mass pressure drop i.e hi pressure liqufied co2(captube before evap) to low pressure enviroment (evap suction side)
http://www.youtube.com/watch?v=4gVzL2pc0Gg
3.by adding another gas to the co2 to make it not quite co2 hence stopping the dry ice forming
4.imo it would just be easyer to use r508 or r23 --each refrigeants have diffrent presures so its hard to say what would be good at the same presures as co2

[[486]]

I should have gone to bed before asking that question. That's what I thought. I was just to tired to really think it through last night.

1.) So what other refrigerants could be used with R-23 in an autocascade?
2.) Why is solidification of R-744 an issue upstream of the capillary tube?
3.) How are people using R-744 without having the icing problem?
4.) What other refrigerants would benefit from operating at the same pressures required by R-744?

Autos are very complex, and hard as heck to charge to the right amount of refrigerant, as adding some of one affects the static pressure and that might change the amount needed of the other. You could probably use a 500 series refrigerant in a 1 refrigerant autocascade, but the boiling points are probably close enough that it wouldn't gain enough to go through the trouble of making an auto...

I remember last year seeing someone running a single stage with a short captube and a big SLHX and a mix of I think R290 and R1150 with a nice big receiver, the propane would run for a while just condensing normally, and then it would cool off the SLHX enough to condense the R-1150. Kinda a semi-autocascade.

[Shingoshi]

1. many
2.because it blocks the cap tube / evap, you should watch this vid it will expslane how co2 responds to mass pressure drop i.e hi pressure liqufied co2(captube before evap) to low pressure enviroment (evap suction side)
http://www.youtube.com/watch?v=4gVzL2pc0Gg

Man have you got me hooked on watching these YouTube videos!
By all means, keep them coming! I can't get enough of these.

So I need to find out what's the minimum pressure required to keep R-744 from icing. If I use R-744 as my first-stage and R-23 as my second-stage, maybe R-1150 could be low-temperature third-stage component for an autocascade.

Shingoshi

[tiborrr]

You just can't use R-744 as a refrigerant for a first stage (high temperature stage) of a cascade! You have to use refrigerant that is capable of condensing within the reasonable condensing pressure range inside of a air cooled condenser - such as R-22, R-290, R-404A/507, R-402B, etc. etc. Please check p-T chart of R-744 and take a look at the pressure @ ambient temperature, e.g. 25°C.

Please, do more reading before you hurt yourself!

[Shingoshi]

You just can't use R-744 as a refrigerant for a first stage (high temperature stage) of a cascade! You have to use refrigerant that is capable of condensing within the reasonable condensing pressure range inside of a air cooled condenser - such as R-22, R-290, R-404A/507, R-402B, etc. etc. Please check p-T chart of R-744 and take a look at the pressure @ ambient temperature, e.g. 25°C.

Please, do more reading before you hurt yourself!

However read this comment and see what I'm thinking about here.
http://www.xtremesystems.org/forums/...9&postcount=22
If it's not possible to condense R-744 with a vortex tube using the right pressure, then at least it will work for R-600a. R-600a has a high enough boiling point that it would condense at the normal temperatures at which a vortex tube operates.

So would R-290 be the better choice, considering how readily available it is (I've read that Benzomatic bottles work well, having high enough purity)? I don't think R-600a would provide enough temperature reduction to condense R-23.

Shingoshi

[[486]]

So I need to find out what's the minimum pressure required to keep R-744 from icing. If I use R-744 as my first-stage and R-23 as my second-stage, maybe R-1150 could be low-temperature third-stage component for an autocascade.

R-1150 is close enough to R23 that you wouldn't need to have a stage in between them, people are condensing 1150 with 290 in the first stage...

I think you would be better served by hiring someone to fix it.

[Shingoshi]

R-1150 is close enough to R23 that you wouldn't need to have a stage in between them, people are condensing 1150 with 290 in the first stage...

I think you would be better served by hiring someone to fix it.

Maybe this is a sliding scale cascade. Kind of like a children's slide, where one kid keeps piling up on the one ahead. It's just a joke. I just couldn't get this out of my head when I read this.

But point taken...

Shingoshi

[ultralo1]

Please, do more reading before you hurt yourself!

Darwinism at work.