Replacing R12

Hello Guys, i'm new in RE and I need some help.
I have this thesis at school and my group currently facing a challenge of replacing the old ac system of a hospital that uses R12. The problem is the hospital management doesn't want to totally replace the system but just to retrofit it to save money. As we all know, R12 will totally be phased out soon, so I'm thinking of a possible solution. Here are my questions:
1. What are the possible refrigerant substitutes to R12?
2. Can I use ammonia as substitute knowing that the ac system is installed in a hospital? Why or why not?

HI ,
R-12 alternative is R-134A which would need minmum system changes . Check if compressor is suitable for ester oil ( used with R-134A) . Retrofitting can be done but need to go in for system details. Ammonia for DX expansion is not suitable for applications like hospital among other applications where human being are present. A remote located secondary cooling might be okay with NH3 , but look for safety aspects.

You can use R-409A

@D.D.KORANNE: assuming safety measures are all checked, can ammonia now be used in a place like hospital??

@chemi-cool: you're right. i'll take your advice.

Thanks a lot guys!

SP34E is a good drop for a hot day

@lowcool: what do you mean??

SP34E is a refrigerant type,same pressure/temperature characteristics of R12,works better on temprite systems than R134A.used it in auto applications and handles high ambient conditions,found it to be a good all rounder as who wants to carry 10 bottles in their van ,i carry six(22,134,507,410,sp34e,reclaim bottle)& thats bad enough i reckon.have a chat to your wholesalers as isceon also make something similar

@lowcool: Thanks! I'll take your advice!

To everyone:
Is Sp34e applicable to commercial applications? I've heard it's only used in automotive ac..??

my apologies for misleading info about pressure /temp characteristic as a mate pointed out,a difference does exist,interesting as last temprite i set was at 27 psi with beer temp temp below zero.

hey Lowcool,

do spe34e come whit an other name to,like R... ,and where can whe find the specs for this refrig. din't find anything at Suva Dupont.

Ice

At first recover the r12 from the system and the retrofit without any changes with r409a.
The pressure are the same that r12.

Quote:

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Originally Posted by icecube51

hey Lowcool,

do spe34e come whit an other name to,like R... ,and where can whe find the specs for this refrig. din't find anything at Suva Dupont.

Ice

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gday icecube
google solpower,they have the rights to this product.is very much the same as 409a

For a start ammonia [ nh3 ] is not an option.
Reto-fitting existing systems with what ever refrigerants, will be a stop gap resolve.
Get along side the bean counter from hospital and explain the big picture, that if they spend money on a total replacement fit-out. You will effectively save the hospital a huge amount of money.
Just a thought. magoo

Quote:

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Originally Posted by lowcool

gday icecube
google solpower,they have the rights to this product.is very much the same as 409a

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havent used 409 for years and never will again it was one of many retrofit gasses of earlier times with chronic discharge temps.