R507 efficiency decrease verses R12

[Chris Moser]

We have some large refrigeration units running on R12 that need to get changed out . Can anyone tell me how much capacity are we going to lose by switching from R12 to R507 ?

[US Iceman]

Chris,

Can you provide an example of one system and the operating temperatures? That might help to make any explanation more meaningful.

PS. Welcome to the RE site.

[Dan]

Chris, you should gain capacity, not lose it. But if you are changing units out, why do you worry about losing capacity, since you should be able to match the new units' capacity to the load. I don't understand your question.

[Chris Moser]

We have a process heat duty of 455 tons of refrigeration being handled by 4 refrigeration units arranged in parallel . We want to convert the units from running with R12 to R507. While I know nothing about the details of what is required to change out the fluid I expected that trying to run at the same operating conditions as we now do with R12 would result in a reduction in refrigerating capacity using the same equipment . So my first thought is how much reduction will I see , and how many of the 4 units will I need to change out completely to recover capacity ?

[US Iceman]

Chris,

What are the operating conditions of the system? Evaporating and condensing temperatures please.

Are you using screw compressors with economizers?

Are you talking about completely changing the systems, or converting them to R-507 from R-12?

[Andy]

We have a process heat duty of 455 tons of refrigeration being handled by 4 refrigeration units arranged in parallel . We want to convert the units from running with R12 to R507. While I know nothing about the details of what is required to change out the fluid I expected that trying to run at the same operating conditions as we now do with R12 would result in a reduction in refrigerating capacity using the same equipment . So my first thought is how much reduction will I see , and how many of the 4 units will I need to change out completely to recover capacity ?

Chris wrong gas to convert to
try R134a, matches the pressures in the old system better. R507 will not work, equipment for R12 is not rated for the higher pressures (the compressors might) but the condensers and evaporators, pipes and valves will all be incorrect.

Kind Regards Andy

[Dan]

Chris, a 4RA-1000 compressor using R12 is capable of 67890 btu/hr at 20 deg F. This same compressor with a larger motor provides about double this capacity at the same conditions with R507. A 4RA-2000 is capable of 122,946 Btu/hr. Same displacement, but twice as much capacity and horsepower. I don't know why you think R507 has less capacity than R12.

If you choose to use the same compressors, you will have to upgrade the motors. You will be abandoning compressors, not adding compressors. You will have to pipe the remaining compressors to the now abandoned condensers. Andy's advice is a much more sensible and less troublesome solution. Use 134A.

[johnyfreon]

R507 is a permanent replacement for R502 and like Andy said its the wrong application for a R12 retrofit,Why don’t you try using 414B? I have used it extensively with great results, it mixes will with mineral oil and the operating pressure are R12 like.