Commercial -150C

[ultralo1]

Last q, buffer tank was the small one or the hugeee one?

The small one is the buffer tank.

Actually you did all the heavy lifting so to speak,

Without your input, it would have taken alot more trial and error. Thanks again.
I still have a little work to do to the charge, the system is slightly unstable with this charge. I believe I added to much 740. The high side slowly creeps up in pressure until it trips the dump valve. The system will warm up to -134C and will get back down to -153C over time. I believe one more recovery and charge will get it.

I also wanted to say thanks to the other members here who have worked with autocascades, for posting their threads for others to read. The information that I have found in them have been invaluable in this little endevor.

If this is for sample storage, is it safe to say the unit is tuned for very low heatloads?

Yes that is safe to say. The perscribed way to store a large amount of samples is to cool in stages (-20Cto -80C to-150C) or use LN2. These systems are not designed for large loads of heat removal.

[n00b 0f l337]

Must still be a couple hundred watts, quite a bit actually. Thats a big box. And insulation losses get big with that sorta thing.

[Tetrafluorometh]

I had to buy a 30 pound cylinder for another project. I had to adapt a fitting for it to use my gauges on. I think I bought the 600 from National welders.

What adapter did you have to use? I really would like to see the HX stack.

How mant KW is the condenser rated for do you think?

[ultralo1]

here is the data sheet

[kayl]

NICE work ultralo1, that is a very cold autocascade

[daliti]

Hello ultralo1, have exactly the same Revco unit to service. Static soak pressure seems fine, so I suspect a capillary blocked somewhere.
How do you suggest to rinse the capillaries?
Disconnect the whole evaporator and rinse it with some sort of degreaser?
Do you want to tell what mixture you finally foudn to be the best?

[ultralo1]

Is this your first Autocascade? Have you worked on Scientific refrigeration before? Do you have the manual? The flushing is extremely tricky on these. You have to use a recover machine capable of handling liquid refrigerants. What is the orginal symptoms?