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  1. Any 404a low temp compressor seems to do pretty...

    Any 404a low temp compressor seems to do pretty well as a low stage compressor with R508b. I've seen all brands used. You just have to keep them cool, which is never a problem in the self-contained...
  2. Your low stage refrigerant (508, 23, 13, 503) is...

    Your low stage refrigerant (508, 23, 13, 503) is never liquid when your cascade system is sitting off at room temp, in 99% of these systems. These things are charged to a static pressure with vapor....
  3. I know a couple different manufacturers that use...

    I know a couple different manufacturers that use it. Seen it on hot gas lines, liquid lines(room temp, subcooled to -40 and everywhere in between), and suction lines that reach all the way down...
  4. Depends what you mean by penetration. It...

    Depends what you mean by penetration. It doesn't(and shouldn't) penetrate in the way a welded join has penetration, but it should run down into the joint the same way solder does. I've seen the...
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    I didn't mean to say they have oil return lines,...

    I didn't mean to say they have oil return lines, they have a little pin hole in the bottom of a trap inside that allow it to siphon oil up into the suction line after the accumulator to return to the...
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    I tend to shoot for 6-8 on freezers and 8-10 on...

    I tend to shoot for 6-8 on freezers and 8-10 on coolers, then verify at least 20° at the compressor. If it's too low then I raise the superheat at the evap. If it's high then I check again at the...
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    Then you've been very lucky to always get valves...

    Then you've been very lucky to always get valves that are sized exactly right for the application or your requirements for superheat are very relaxed. Those valves are good for a range of tonnage,...
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    ^ Not going to adjust it after it's installed...

    ^ Not going to adjust it after it's installed then?
  9. Best collection of information on capillary tubes...

    Best collection of information on capillary tubes ever compiled:
    http://www.supco.com/images/pdfs/Manuals-Instructions/Cap%20Tubing%20Manual.pdf

    Read it, it's fascinating and it explains what...
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    I can offer a little insight on the subject of...

    I can offer a little insight on the subject of sound, since that's one of my hobbies... "Twice as loud" is an increase of 3 dB.

    In the car audio/home theater world, it's pretty common knowledge...
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    That level of vacuum isn't likely to hurt it, but...

    That level of vacuum isn't likely to hurt it, but it's not going to end up there. 6-8" maybe. Take a little bit out and see what happens. You're not going to kill it.
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    Running in a vacuum isn't a problem. It's not a...

    Running in a vacuum isn't a problem. It's not a good idea to start a brand new compressor while it's under a deep vacuum (30") but a running compressor even down to 15" isn't all that abnormal in...
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    It's usually a pretty good policy. As mentioned,...

    It's usually a pretty good policy. As mentioned, your mixture doesn't follow a pressure/temperature chart anymore. There's a pretty successful manufacturer of laboratory equipment that has been...
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    I doubt it's illegal. 70% of the ultra low temp...

    I doubt it's illegal. 70% of the ultra low temp and laboratory refrigerator/freezer market is equipment that comes straight out of the factory with mixed gases...
  15. Thanks, I couldn't remember how they were piped....

    Thanks, I couldn't remember how they were piped.
    I came up as a younger tech servicing environmental chambers (which were installed when I was a child) that used those Copeland C-line condensing...
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    Any standard (normally closed) solenoid valve...

    Any standard (normally closed) solenoid valve actually functions pretty well as a check valve when it's not energized.
  17. They still sell units like that. (apparently not...

    They still sell units like that. (apparently not many though cause I haven't seen a new one in 10+ years) The copeland C-line has the dual receiver base similar to that old school setup.
  18. Thread: subcooling

    by cmclifton
    Replies
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    2,982

    Sure about that? Edit: nevermind, yes there is...

    Sure about that?

    Edit: nevermind, yes there is a noun form of the same word. the liquid is a saturate. as is the vapor. the point I was making was about the vapor and liquids being at different...
  19. Thread: subcooling

    by cmclifton
    Replies
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    2,982

    Same silly argument, different day. We all know...

    Same silly argument, different day. We all know that you can have vapor with subcooled liquid laying underneath it, nobody wants to admit it because they've been telling people all their lives that...
  20. Obviously, you know everything you need to know....

    Obviously, you know everything you need to know. Why are you asking for help?
  21. I can say for sure that they were still using the...

    I can say for sure that they were still using the exterior mounted handles around 98-99, but I don't know when they actually got changed.
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    As long as we still need freeze driers in...

    As long as we still need freeze driers in biotech/pharma, there will always be compound compressors. Carlyle hasn't stopped making them and probably shouldn't. We don't need more reasons to buy...
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    I wholeheartedly disagree that the plumbing of...

    I wholeheartedly disagree that the plumbing of that liquid line will cause uneven feeding. You've got a full column of liquid being held back by a TEV on either evaporator. Those TEVs are going to...
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    Nothing needed aside from standard good piping...

    Nothing needed aside from standard good piping practices.
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    ^^My thoughts align EXACTLY with PHM up there.

    ^^My thoughts align EXACTLY with PHM up there.
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    ^Ive been told by several old school guys that...

    ^Ive been told by several old school guys that they never unsweat a drier for that exact reason.

    The only time I remember reading about a drier being baked in an oven on this site was because a...
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    and dont ever drop them. ever.

    and dont ever drop them. ever.
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    I feel like any penetrating oil that actually...

    I feel like any penetrating oil that actually works well is going to stink like that though...

    I carry Kroil in my truck and swear by it. Works well enough that you can use a TINY bit to do the...
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    The supply houses should all be able to get you...

    The supply houses should all be able to get you 502, but I doubt they keep it in stock these days. If I were buying some, I'd get it from ebay or some other place online as cheap as possible. A 30#...
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    You can also take your amp clamp (meter) and open...

    You can also take your amp clamp (meter) and open it, put the jaws around the coil so that one jaw is at the top and one is down near the bottom. Think like you're trying to get the jaws around the...
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    I've been around systems using HC refrigerants...

    I've been around systems using HC refrigerants off and on since I was brand new. It's really not tough to deal with. Run a hose outside, purge nitrogen, cut things out instead of unsweating...

    The...
  32. ^ No new installs with HCFC refrigerants due to...

    ^ No new installs with HCFC refrigerants due to the phase out... Maybe doesn't apply here?
  33. Worn contactors on 3-phase compressors can ground...

    Worn contactors on 3-phase compressors can ground them. (Single phase the motor and it's toast very quickly)

    Floodback can do it.

    Low side leaks on systems that run in a vacuum eventually do...
  34. Take any fan blade, flip it over, and the blade...

    Take any fan blade, flip it over, and the blade pitch is still in the same direction. It still flows air one way, only less efficiently in the case of a typical evap or condenser blade.

    A ceiling...
  35. It happens even with the big money biotech...

    It happens even with the big money biotech companies too.

    I recently spent 4+ months working on a freeze drier that had been sitting unused for TWO YEARS. It was sitting idle because the person...
  36. We cut one open at our shop after it restricted...

    We cut one open at our shop after it restricted completely. Total blockage. Found the desiccant encased in what looked like epoxy. We just figured that must be what happens when you put too much of...
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    Cincinnati Sub Zero makes test chambers with...

    Cincinnati Sub Zero makes test chambers with 410A. They have one with a compound compressor that will make -50°C on 410A. It looks like a great low temp refrigerant when you're looking at the PT...
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    I've got a cascade process chiller with redundant...

    I've got a cascade process chiller with redundant compound Bitzer compressors for the low stage. -47°F, also R507. Interstage suction cools a plate heat exchanger to subcool the liquid line before...
  39. Thread: r12 walk in

    by cmclifton
    Replies
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    2,878

    Coalescing oil separators, and just the simple...

    Coalescing oil separators, and just the simple fact that there's no oil left in the stream by the time you get past the last receiver and heat exchanger. The argon doesn't carry the oil the way the...
  40. Thread: r12 walk in

    by cmclifton
    Replies
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    2,878

    The overall COP... I haven't the slightest. I...

    The overall COP... I haven't the slightest. I wouldn't expect it to be good. 3 horse scroll to cool 5 cubic feet with something like 80% "on time". The rest... tbh I don't have the vocabulary to...
  41. Thread: r12 walk in

    by cmclifton
    Replies
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    2,878

    In the case of a Thermo -150 freezer, that argon...

    In the case of a Thermo -150 freezer, that argon does get somewhat condensed. It never becomes a full column of liquid, but it's not just there to keep pressures up. It's the argon that cools the...
  42. Thread: r12 walk in

    by cmclifton
    Replies
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    2,878

    I work on those things too. (-150 is a little...

    I work on those things too. (-150 is a little more common) You can't measure superheat and you know it.

    One of those refrigerants is argon. You're not ever going to get a Copeland engineer to be...
  43. Thread: r12 walk in

    by cmclifton
    Replies
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    2,878

    I know this is a waste of time, but I have to see...

    I know this is a waste of time, but I have to see this play out... What refrigerant is in that mythological piece of equipment that has 20 degrees superheat and 80 degree return gas?
  44. Thread: r12 walk in

    by cmclifton
    Replies
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    2,878

    Don't try too hard. There's very little logic...

    Don't try too hard. There's very little logic involved in checking subcooling on systems with receivers and ignoring superheat at the compressor ...And then calling the return gas temp measurement...
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    Me too :) the Wikipedia link was an afterthought....

    Me too :) the Wikipedia link was an afterthought. "Wait what if he's being serious?"
  46. Replies
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    Subcooling is what fools people into thinking...

    Subcooling is what fools people into thinking they're fully charged when they've got a flashing sight glass and nitrogen in the top half of their condenser coil...
    ...
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    I'd hope so, but I've never seen a rack at full...

    I'd hope so, but I've never seen a rack at full capacity. I never got to do anything but service work on existing stores. I'd consider myself a complete failure if I let enough cases warm up to bring...
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    Now there's a good question. An R507 rack at...

    Now there's a good question.

    An R507 rack at ~30% capacity will definitely make you ponder that one. I think it's only there so you can look in there and imagine what it would feel like to be a...
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    Stop it. You're going to give someone a heart...

    Stop it. You're going to give someone a heart attack. :Faint:
  50. Replies
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    What it does mean is that you don't get to...

    What it does mean is that you don't get to change what the subcooling is unless you have an active subcooling system (compound compressor or separate subcool system maybe). The fact that you have a...
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