Help with a Ransco cascade cabinet on R13?

[garyb]

Hi All

One one our clients has picked up an old Ransco thermal shock testing cabinet off Ebay and I need some assistance with it. The model is 7102-3, serial number 3855 and was built 4/82. After you stop laughing at me - I'm trying to find a manual or at least some data on the charge for each stage. From what we can tell the high stage is R502 and I think the low may have originally been R13 but that's a guess. I know R13 (and R23?) was commonly replaced with R508B and I recall years ago doing some work on a Forma Ultra-Low that used ethane on the low stage. We are more familar with the big stuff so there is a lot of guessing and assuming going on at present.

Specifically;
1. What refrigerant is the low stage on? How much? What oil will the new refrigerant require?

2. What refrigerant should we replace the R502 with? R507? The compressors are small semi-hermetics so oil changing shouldnt be a problem.

3.What are typical running pressures for this type of cabinet?

4. Does anyone have a manual for this model?

Thanks in advance.
Gary

[Polypete]

Hi Gary, I don't have particular details on the units you mention but I do have experience with 3 stage cascades and a 2 stage unit which was very similar. Our 3 stage units ran on R502, R13 and R14. The 2 stage ran on R22 and R23. We converted the first two stages of the 3 stage units to run on R22 and R23 when CFCs were first banned. The only change required was the oil in the 2nd stage compressor which was changed to a polyolester type. You will also need an additive to carry the oil through the evaporator. An addition of 3% (of the refrigerant charge weight) of Ethane should do the job. Does your unit use TEVs or capillaries ? I can give you some idea of expected running pressures (gauge tempereatures) if needed, Pete.

[heyejun]

Hi Gary,I think you can replace the R502 with R22,and the oil needn't replace. The R13 can be replaced with R23.The importance notice is you must add a bigger inflating vessel,and replace the oil with EMKARATE RL32H.

[Rob S]

Work on a couple 7010s...
I charge the high stages with 507 till fill sightglass. Chilled watercooled condensors H2O valve set at 225psig. Suction runs like a normal freezer.. 20 to 10psig
Then charge the lowstage with 508B to 115psig static.
Head pressure will run 230psig+ at full load. Suction will be around 25psig. Both head and suction will drop at low load.

What are the top and bottom heating element KW?
Going to stop here... Because the two work on are not stock by anymeans. The workings have been changed.

Haven't had to do any chamber or ultra-low conversions for some time.
502 to 507 or 404A POE 22 (150vis oil)
13 or 503 to 508B POE 22 (150vis oil)

Basicly use 80% of the charge for both 507 and 508B.
508B is just 80% of listed static.
Sometimes 85% works better...

[garyb]

...The importance notice is you must add a bigger inflating vessel...

What is an inflating vessel?

[US Iceman]

If I had to guess, I think the person meant expansion tank for the low temp. system.

[john lawler]

Hi All

One one our clients has picked up an old Ransco thermal shock testing cabinet off Ebay and I need some assistance with it. The model is 7102-3, serial number 3855 and was built 4/82. After you stop laughing at me - I'm trying to find a manual or at least some data on the charge for each stage. From what we can tell the high stage is R502 and I think the low may have originally been R13 but that's a guess. I know R13 (and R23?) was commonly replaced with R508B and I recall years ago doing some work on a Forma Ultra-Low that used ethane on the low stage. We are more familar with the big stuff so there is a lot of guessing and assuming going on at present.

Specifically;
1. What refrigerant is the low stage on? How much? What oil will the new refrigerant require?

2. What refrigerant should we replace the R502 with? R507? The compressors are small semi-hermetics so oil changing shouldnt be a problem.

3.What are typical running pressures for this type of cabinet?

4. Does anyone have a manual for this model?

Thanks in advance.
Gary

hi,

i find that r408a is the best drop in gas for the old r502

[rublet]

Hi garyb

I work on a lot of cascade thermal shock chambers and our own systems used to use R502 we have now replaced it with R403B with no need for expansion valve or oil change.
The low stage can be charged with R23 and polyester oil.
Typical running pressures are High Stage LP 1.5-2.5bar HP approx 10-15bar
Low Stage LP 0.1-1.5bar HP 16-20bar