Cascaded Systems

[ultralowtemp]

HI. I service a lot of cascaded refrigeration units and want to know more about changing refrigerants and compressors in these systems.

I am looking for a really good book or source about these systems. Practicle yet in depth. At this moment I am looking for a practical method of sizing capillary tubes for R508B etc. when used in the ultra low temp range.
Also refrigerant metering according to text I have is supposed to be isenthalpic during the process. According to Copeland literature for a KAK1-0100-TAC their figures show more BTU/HR than an isenthalpic throttling would produce. Any comments on how to predict the effective latent heat of evaporation when going through a cap tube or txv?

[jcook1982]

I find a lot of good information on this site.. Unfortunately cascade is such a specialized industry that finding this type of information on here may be difficult. This type of information may be easier acquired from a manufacturer, the manufacturer may have a direct drop in replacement refrigerant for their systems. I currently work at a manufacturer and when people call in about our older units and say they can get a certain refrigerant any more i have direct drop ins to recommend so there is no cap tube sizing and such...

[Emmett]

Ultralow,
Jcook1982 hit the nail on the head.
I have worked for a manufacturer in the past and currently work on several brands in one facilty. Many of the manufacturers are willing to share information with you regarding their product, I would start with them.

[norseman]

If you would like to get a training also containing some good servicing manuals, you could try the Thermo Fisher group. They produce a lot of ultra deep freezers of different brands like Thermo and Revco with others. Just those two brands are likely to be the biggest maker to the market in USA. I have joined quite some trainings over the last 20 Years by them. I am sure that you could ask for a training course and get it except for if you serve mainly Sanyo products from Japan;) They have a very long experience and go from the basic and up to more tricky issues.
As mentioned earlier on the board, the producers,
most of them anyway, makes pretty good manuals containing retrofit, charging information and on. To calculate capillary tubes do I trust them and lucky enough does not need to find my own.
It si a very interesting field with a lot of different solutions of making those beauties to hopefully run well and for a reasonable time. I have been into may be 30 differnt producers and a lot of different models over the Years and find that most of them have their own "personality" in good and bad. A lot of failures has been learnt the hard way. I think experience and oppertunity to work with many of such systems will make you to be an "expert" over time. A lot of fun out there as freeze driers, test chambers, cold traps etc. You get a field of work of speciality who can make you important and that is not too bad.
Norseman

[jcook1982]

If you would like to get a training also containing some good servicing manuals, you could try the Thermo Fisher group. They produce a lot of ultra deep freezers of different brands like Thermo and Revco with others. Just those two brands are likely to be the biggest maker to the market in USA. I have joined quite some trainings over the last 20 Years by them. I am sure that you could ask for a training course and get it except for if you serve mainly Sanyo products from Japan;) They have a very long experience and go from the basic and up to more tricky issues.


If you don't push Thermo Revco don't expect them to train you.. instead they push out the independents by having their own guys placed in the area.

I'm sure any manufacturer has plenty of information. Just find their number on the internet or on the unit your working with. It should be somewhere near or on the nameplate of the unit. :cool:

[norseman]

If you don't push Thermo Revco don't expect them to train you.. instead they push out the independents by having their own guys placed in the area.

I'm sure any manufacturer has plenty of information. Just find their number on the internet or on the unit your working with. It should be somewhere near or on the nameplate of the unit. :cool:

jcook.

It was strange to read your "love" for Thermo. I am not situated in the states so I can not argue with the problem that they push people out of the
business. I have met many guys both local and international and never heard about it. You dont have to sell your soul to them or your clients I suppose :o The good thing in this business is that most of the producers make a label who contains the most imprtant issue, the charges of the unit with the static pressure on the low stage. Some few gives is as an after run pressure and others as a new charge pressure. Several gives also a complete refrigeration drawing and the electric schematic supplied on the unit either as a label or in a bag back rear. The wisdom from the supplier can be a more tricky case both due to the willingness against an "outsider" and how competent they are, specially abroad. Revco made some manuals 30 Years ago who explained both servicing cascades and their products so good that they still is one of a kind. The time changes and the products and behaviour are not as good to handle now. The best manual I have seen the later Years is from Sanyo autocascade systems like on -135 and -152c. They gave so good details as a bible and gives a "stranger" confidence to investigate and work on such complicated systems. Long story!

PS: A good site to find the refrigerants and oil who goes for them (cascades) is the German compressor company Bitzer( bitzer.de) Even in Russian I think.