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mark957
01-02-2013, 08:54 AM
Greetings to all
I retrofitted a unit cascaded to the second stage with a final temperature of -90 C. the system had a load of 1 kg with 0.1 kg R503 R12.
I replaced the oil with oil poe, and primed, 1 kg 0.1kg R23 with R134a.
after the test run the final temperature reaches -65 C.
can someone help me with similar experiences?
which you think may be the right mixture of refrigerant retrofit?
Thank you.

mark957
10-02-2013, 09:37 AM
experts please help me.

& thanks in advance

NoNickName
10-02-2013, 11:51 AM
With R134a is quite impossible to reach -90C.
You had to use R23, but then again it is impossible to say, unless you give complete description of components, exchangers and compressors of the two stages.

RusBuka
10-02-2013, 02:03 PM
You can use ethylene for 2 steps, if you find)

mark957
11-02-2013, 08:01 PM
Thanks for the answers
What do you think if I use the refrigerant R508B?