R-417A as drop in for R 22

[Jan-Willem]

Currently I experienced an industrial refrigeraration installation running on R-417A. As I was told this refrigerant is used as a drop in for R-22. However the end-user wasn't happy at all since he had to pay for 3 compressor overhauls over 1 year.
As independent advisor I was asked to analyse this problem. So far I took the job but until now no results. Who can help me with this problem or is willing to share his experiences with this refrigerant. Some specifications;

System; two stages with liquid subcooler
T low; - 50 Celsius
T intermediate; -10 Celsius
T high; + 35 Celsius
Oil; Suniso 4 GS (mineral)

[chillyhamster]

Whilst this may be a drop in refrigerant, National refrigerants recommend that POE oil is used.

[Peter_1]

Why did the previous compressors broke?
Mechanical and/or electrical damage?
If mechanical, sort of internal damage of the compressor/pistons, crankshaft?
How many oil in the sump after a failure?
This can be very usefully to determine the cause of the problem.

When running,... what pressures, temperatures of high, low and intermediate side?

Jan-Willem, kijk eens op http://www.dehon.com/nl/index_nl.php...ion=3&idn3=166 en vraag misschien eens hun advies.

[Peter_1]

You may use them, I won't use my copyright rights
May I ask, where somewhere on your pages?

[Peter_1]

In that case, I wil make more pictures from broken parts I encounter. Never thought they could be used for something.
Need some more, more close-ups?

[Jan-Willem]

What are the compressor wear patterns?

Take lots of photo's. I need photo's for my web based article illustrations. Have actually used some of Peter's photo's already

http://fridgetech.com/articles/recipfailmodes/

Dear Marc,

Thanks for your reply and the link to your outstanding technical web page. The compressor wear patterns are concerning all rotating parts. The most significant wear is located on cylinderliners, conrods and crankshaft. The most obvious reason for this damage is liquid flood back. I've really got some bad thoughts about the adjustment of the TEV. R-417A is a refrigerant with a huge glide. While adjusting the superheat you've to consider the impact of the glide, in this case up to 10K!! To ensure a superheated suction gasflow you've to add the glide + the normal superheat 4-6K at least. In my case you've to measure a suction line temperature of at least -36 Celsius (To=-50). Please give me your opinion on this.

[Jan-Willem]

Dear Peter,

Thanks for your reply. I've to investigate the amount of oil left in the sump after compressor break down. However I'm sure it must be about nothing due to the cause of liquid flood back. What else can it be? Please read my reply to Marc O'Brien in order to receive your opinion about my thoughts. And above that can you inform me if you've to change the TEV during a R-417A retrofit. Regards, JW

[Peter_1]

... I'm sure it must be about nothing due to the cause of liquid flood back. What else can it be?

Jan-Willem,

We don't know nothing what happened with the prvious compressors.. broken valves, ***** wash-out, slugging, flooding back, oil pumpfilters clogged, oil pumps broken, liquid hammer, oil hammer due to a huge sudden oil return, electrical failures all sorts... you see, it can be anything.

Have a look at http://www.rmsgas.com/cr417aoverview.htm They state that nothing has to be changed but indeed, I notice now also the enormous glide of 10K.

Have you monitored the new compressors?
You said in your first post,.. nor result . Was this with the new machines?

Are liquid seprators mounted of sufficient capacity?

Hot gas defrost perhaps?

Why not change it immediately to R507? I have no confidence in all that commercial blablabla if you have a glide of 10K. Too difficult, in fact almost impossible if you ask me to regulate the TEV so that it senses correctly.

The pictures Marc used from me are from a R22 Demand cooling which was converted to R404a!
2 compressors broke at that plant!