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R13B1 - Small VLT Unit Troubleshooting

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fairly

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Discussion starter · #1 ·
Hello Everyone, long time, first time here.

Please let me know if this isn't appropriate for this forum.

I've come across an interesting piece of lab equipment on a surplus sale: a single stage VLT cold trap running R13b1. Its an oddity I'm playing with for entertainment value only.

It's an old unit: capillary tube metering and no external tstats, it just runs until the compressor trips its thermal overload, somewhere around 115C (240 F).

So here's what I know:

Compressor is pulling exactly one amp above its run rating: 4.5A instead of 3.5A.
Condenser is clean, fan is working fine.

I've run it with no load (empty trap) and with load (room temperature isopropyl alcohol), no difference.

Trap reaches temp of -20C and holds there after about an hour when it should be hitting around -50C. I can see the return line from the evaporator covered in frost at that point.

Condenser input temp: 74.3 F
Condenser output temp: 66.3 F

Evaporator is a sealed unit, can't pull any readings there.

Next step is piercing the lines and taking a manifold reading, at which point I'd be bottling up the r13b1 and considering replacements...

I was wondering if anyone here would have any thoughts on the matter (or know what lubricant is used for halon refrigerants)?

Cheers!
 
#2 ·
It's possible and very likely the refrigerant that's in this unit is something other than R13B1. Have you checked the Pressure/temperature relationship to try to verify or ID what refrigerant you have there?

I have little experience with VLT but I did a retrofit on a freeze drier unit from R13B1 to R403b (DuPont Isceon 69L) and it worked quite well for -50°C. It had a standard Tecumseh compressor with 150 SUS mineral oil.
 
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Discussion starter · #3 ·
All signs indicate this is a virgin unit, all access ports are stock, lines look to be original, no piercing valves, or any signs of brazing outside of original assembly.

I have worked on similar units in the past where it was clear that compressors were replaced and refrigerants swapped over, primarily due to the aging differences in the copper and compressors themselves (danfoss sc12b vs sc12clx for example). Even easier, the stickers on the outside of the unit would be lovingly updated to reflect their new contents.

If I had access to 403b, or even r13b1 for that matter, I'd be more gung-ho about jacking into the system to grab superheat readings, but given the age of the compressor (likely leaking reeds) I'm afraid piercing into the system will leave me with a total dud, rather than an underperformer.

I'm waiting on some quick-connects so that I can get some readings without having to use the manifold.

I've seen some old Halon 1301 fire extinguishers and from what I can gather, they are a 13b1/Nitrogen mix, does anyone know anything about these? Ie, are they really a mix, or is the nitrogen an insoluble propellant?
 
#5 ·
fairly said:
Also, can you share the 403b retrofit details? Cap tube changes, charge pressures, etc?
Click to expand...
The one I did I used the basic information I got from the manufacturer like the new cap tube size, to solder the cap tube to the accumulator (like it was from the factory) and the approximate charge. Other than that, no oil change or other mods were needed.

I can't find the DuPont reftrofit info for their Isceon 69L, but here's a link to some info from Linde:

http://www.linde-gas.com/en/products_and_supply/refrigerants/hcfc_refrigerants/r403b/index.html
 
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#6 ·
:hijacked:Okay forgive my ignorance and maybe this needs to be in pro’s but what’s the difference between r13 and r13b1. I see b1 is referenced as halon and I see national refrigerants uses r22 as reference. I have used r13,23,508 and the like, and see no comparison to r22 even in the days of low temp racks.That being said why not retrofit to r508b .
 
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#7 ·
crazzycajun said:
:hijacked:Okay forgive my ignorance and maybe this needs to be in pro’s but what’s the difference between r13 and r13b1. I see b1 is referenced as halon and I see national refrigerants uses r22 as reference. I have used r13,23,508 and the like, and see no comparison to r22 even in the days of low temp racks.That being said why not retrofit to r508b .
Click to expand...
Used to be that if you wanted a 502 unit to run 10 degrees colder, you would put in 13b1.
 
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#8 ·
Never heard of that guess that kind of explains the 22 reference kind of I’m assuming this was a way to get all you could without going cascade? Now the Phm in me wants to add some to 404 just for the hell of it jk.
 
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#9 ·
crazzycajun said:
Never heard of that guess that kind of explains the 22 reference kind of I’m assuming this was a way to get all you could without going cascade? Now the Phm in me wants to add some to 404 just for the hell of it jk.
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It doesn't combine well with other refrigerants. Ask me how I know.
 
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#10 ·
Good info as always thanks guys
 
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#12 ·
LOL

Not really necessary at this point. It's way above any homeowner or DIY stuff. There are these systems out there that mix several refrigerants to get -100 to -150*C, but the kicker is, there is only one compressor. There is a 'slang' term for it, but those drawings for plumbing [when Googled] are not accurate. The manufactures try to keep things close to the vest. But anyone can buy one, take it apart, then reverse engineer things.

The piping is pretty trippy, even the patent doesn't really reflect how it is really plumbed. Anyway, in an effort to make an environmental chamber do more than it was designed to do, I was playing around. Looking for the best combination of refrigerants, then when adding the R-13b1, something chemical happened and the head shot up super fast.

For fun, Google patent 3,768,273.

And for even more fun, just to see them do this with what I call 'gasoline' in the early 1900's, Google this patent: 2,041,725. They were doing these things with low side floats. Pretty freakin' cool.

Anyway, this segment of our industry is a bit specialized.





crazzycajun said:
Sounds like a good story for the pro section
Click to expand...
 
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#13 ·
I’ve read about those never had a chance to work on one. ( good thing looks like I would have that all fubared)
 
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#14 ·
BBeerme said:
LOL

Not really necessary at this point. It's way above any homeowner or DIY stuff. There are these systems out there that mix several refrigerants to get -100 to -150*C, but the kicker is, there is only one compressor. There is a 'slang' term for it, but those drawings for plumbing [when Googled] are not accurate. The manufactures try to keep things close to the vest. But anyone can buy one, take it apart, then reverse engineer things.

The piping is pretty trippy, even the patent doesn't really reflect how it is really plumbed. Anyway, in an effort to make an environmental chamber do more than it was designed to do, I was playing around. Looking for the best combination of refrigerants, then when adding the R-13b1, something chemical happened and the head shot up super fast.

For fun, Google patent 3,768,273.

And for even more fun, just to see them do this with what I call 'gasoline' in the early 1900's, Google this patent: 2,041,725. They were doing these things with low side floats. Pretty freakin' cool.

Anyway, this segment of our industry is a bit specialized.
Click to expand...
What you describe is an auto-cascade system, the basic for which is explained here by Garth Denison when he was at Sporlan:

https://icemeister.net/backroom/wp-...wp-content/uploads/2015/04/ColdWar-February-2007-Auto-Cascade-Refrigeration.pdf
 
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#16 ·
That is the 'easy' way, but not the fastest. After awhile, you can get pretty good at getting a system back on line ASAP. For example, the the high side is too high, then you add the higher temp refrigerants. If the pressures are too low, you add the low temp refrigerants.

It's real easy to over charge when doing this. Meaning, that if the system turns off, the standing static might be too high for the compressor to restart. So you have to be very careful when doing this stuff out in the field.


daneel404a said:
Can I assume that to charge an auto cascade system would require a purchase from the manufacturer with the proper weighted blends for the specific unit in one tank?
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#17 ·
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#18 ·
BBeerme said:
Yeah, I couldn't remember the name. That piping is for concept only, in practice though, the plumbing doesn't look anything like that.
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True that, but it's a schematic piping diagram of the system and as such, it no more resembles a real system than does an electrical schematic or a ladder diagram looks like the actual wiring. ;)
 
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#20 ·
BBeerme said:
That is the 'easy' way, but not the fastest. After awhile, you can get pretty good at getting a system back on line ASAP. For example, the the high side is too high, then you add the higher temp refrigerants. If the pressures are too low, you add the low temp refrigerants.

It's real easy to over charge when doing this. Meaning, that if the system turns off, the standing static might be too high for the compressor to restart. So you have to be very careful when doing this stuff out in the field.
Click to expand...
Interesting, thanks. We have a lot of -80C's here but haven't come across an auto cascade yet to look at the label.
 
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