Minus 86 deg medical freezer

[ltscrash]

Hi ,
Currently working on a - 86 deg cascade freezer.
Forma scientific Model 958 serial 87562.
High side is ok running R 134 a. Low side blew a compressor replaced and need to re charge , i think it is running R23 , but R290 is also mentioned on the id plate , most details are worn off . I also have no wiring diagram.
Any help would be appreciated.
I am In Vientiane , Laos so everything must be imported form Thailand or elsewhere
Regards
Chris burrows
MD
Lao Technical Services

[Sturt]

Hi Chris

Is it a double or triple cascade system?

Three refrigerants would point to triple cascade for sure but you will need to identify which stage you are working on and confirm refrigerant type and amount.

I would suggest going back to the manufacture to confirm if you are able?

Maybe somebody else will have more experience to help you.

Sturt.

[ltscrash]

Double cascade sytem , I am working on the low temp side.
it refers to R23 and R209 on the name plate but it is difficult to read.
I cannot get an answer from the manufacturer.
Now called Thermo Scientific.
Regards
Chris

[Sturt]

Hi Chris

Thermo Scientific still trade separately but are now under the Fisher Scientific umbrella.

www.fisher.co.uk

Tech support: 01256 817282

Good luck - let us know how you get on.

Sturt.

[ltscrash]

Yes Thanks Sturt , I have sent an email . hope they respond.
Any Idea on what the replacement refrigerant is for R23 ? now, Very high pressure, guess thats why its on the low temp side.
Low temp compressor starts 10 min after the high temp side gets going.
Regards
Chris

[chemi-cool]

R-23 is HFC, It is a replacement for R-13 and 503.

[thebigcheese]

hi mate do alot of this work are u still strugling? i do a site with around 13 of the thermos.

[ltscrash]

Hi Cheese,
I am not doing anything to the freezer at the moment , witing for more information. Are you working on the same models?
What compressor and refrigerant are they using in the low temp system?
Thanks for any help
Regards
Chris

[ltscrash]

Yes still having problems . i need to find out the type of refrigerant used on the low temperature side ?
Thanks
regards
Chris
LTS
Laos

[ltscrash]

Sorry , did not refresh the page.
Is r23 used on the low temp side of these freezers?
regards
Chris

[CONROD]

r290 is probably a very small addative to the r23 (MAIN REFRIGERANT), to aid with oil circulation @ those low temps.

[ltscrash]

Ok , makes sense, I wondered why they had propane in it.
R23 is 84000 Baht / $ 2400 USD for 8 Kg in Bangkok . 300$ USD per Kg ! are they taking the piss?
What is the price in the real world? Is R13 still avaliable?
Thanks
and Regards
Chris
LTS
Laos

[thebigcheese]

mate the price on those gases is usaly higher, give me a few days and il see if we have retro fitted any

[Magoo]

Itscrash.
had a similar medical cabinet that was treble cascade and propane as the low stage, finally got a 1 Kg bottle off the local industrial gases supplier, but stipulated zero moisture content, as in super refined. They fronted with a small bottle similar to an oxygen bottle that you see around hospitals. was expensive. After fixing the leak on low stage, evacuated 6 times, each time breaking vac with moisture free nytrogen. Charged system to a specified standing pressure at a given ambient. It worked a treat, -100 odd degrees, friggen scary stuff propane. I think these days they would be using CO2 as the low stage.

[mayankjindal]

Hi chrisis,
This is Mayank Either you use R508B instead of R23 and R290. It is a better option. we are making -86 freezers here in INDIA.

Or you can use R507 about .580kg. and R170 about .079kg.

But still will suggest to use R508B

Best Regards
Mayank Jindal