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  1. #1
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    Dec 2010
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    nitrogen to purge oil?

    Question for you guys that deal with chillers out there often:

    I have an r-22 acme 150 ton chiller that is in our lab, we use it for students to get some time on a chiller. Problem is, the last group that went through filled it so full of oil that it is coming out the access port. The drain plug is positioned in such a way that it is a real pita to drain without making a mess. I have all the pieces needed to make a drain tube down with a shutoff so that we can simply hook a hose up and drain it easily, but i still have a ton of extra oil in the system.

    My question is.. can i use a bit of nitrogen (this doesn't have a low pressure disc) to pressurize the compressor while isolated (already recovered refrigerant from the oil) to essentially pump the oil out into a vessel?

    thanks in advance for your time, guys.

  2. #2
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    Jan 2011
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    Russellville, Alabama
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    I think if it were me, i'd be more inclined to pull a vacuum on a small vessel of some kind that isn't being used and has a good drain location on it, then use a small hose with a shutoff valve connected to it to submerge in the lowest point of the chiller. It'll remove oil very well....

  3. #3
    Join Date
    May 2004
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    fwiw I'm far from a chiller guy, I'm jus a grunt that works on a little of everything, and sometimes even fix it haha.

    I'd second the vacuum idea too. Should be a more controllable, less messy and more proficient way to do it.

    Their mistake is actually a good one, because at some point they will run into this in the field and have to do this.
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  4. #4
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    why don't you pump it down, recover the refrigerant out of the compressor body, bringing it into a vacuum, and swap out the plug with a valve on the fly?
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  5. #5
    Join Date
    Dec 2010
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    Eaton Rapids, Mi
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    Quote Originally Posted by heavymetaldad View Post
    why don't you pump it down, recover the refrigerant out of the compressor body, bringing it into a vacuum, and swap out the plug with a valve on the fly?
    well, it was pumped down and recovered, but i don't see the point of pulling a vac if i'm going to swap the plug.. wouldn't it make more sense to swap the plug and THEN pull a vac?

    turns out there was no need to remove any oil, there was 10 or so pounds of refrigerant that migrated to the oil. removed that, and the oil level was actually a little low.

    I was just curious if you could pressurize oil safely into a recovery tank with a vac on it. The unit in question has a service port on the oil fill hole, and it'd be really easy to put a hose on there.

    Thanks for the suggestions, though!

  6. #6
    Join Date
    May 2008
    Location
    Central Pennsylvania
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    Quote Originally Posted by seuadr View Post
    well, it was pumped down and recovered, but i don't see the point of pulling a vac if i'm going to swap the plug.. wouldn't it make more sense to swap the plug and THEN pull a vac?

    turns out there was no need to remove any oil, there was 10 or so pounds of refrigerant that migrated to the oil. removed that, and the oil level was actually a little low.

    I was just curious if you could pressurize oil safely into a recovery tank with a vac on it. The unit in question has a service port on the oil fill hole, and it'd be really easy to put a hose on there.

    Thanks for the suggestions, though!

    Heavy's suggestion of pulling the compressor into a vacuum before you swap out the drain plug was so that you wouldn't have to worry about that oil mess you we talking about.

  7. #7
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    Dec 2010
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    Quote Originally Posted by chillerguy81 View Post
    Heavy's suggestion of pulling the compressor into a vacuum before you swap out the drain plug was so that you wouldn't have to worry about that oil mess you we talking about.
    would the vac really hold long enough for me to totally swap the pieces?

  8. #8
    Join Date
    May 2008
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    Central Pennsylvania
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    Quote Originally Posted by seuadr View Post
    would the vac really hold long enough for me to totally swap the pieces?
    Sure, as long as you have the access to spin the old plug out and the new valve in. Have you're new valve and nipple all ready to go with leak lock (or whatever you like to use), old one out and new setup in, in a few seconds if everything goes right.

  9. #9
    Join Date
    May 2001
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    Western Wa
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    I also recommend installing a service valve in place of the drain plug. It will come in so handy for things like sampling or adjusting the level. This would be a good teaching point on oil management and the various conditions that cause the oil to take off out into the system.

    However, I refuse to use Leak-Lok, and would use only the Loc-Tite refrigerant thread sealer for something like this. I have seen way too much misuse of Leak-Lok locally, like a highly touted contractor whose installer used it on flare fittings, making up line sets. I use only refrigeration oil on flare fittings. The correct sized wrenches and a good tightening.

    Also bone up on the EPA regs regarding adding and or removing compressor oil.
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  10. #10
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    Heavy's trick will work very well I have done a charging valve on a large low pressure chiller without losing a drop of freon just have to be quick.
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  11. #11
    Join Date
    Dec 2010
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    Eaton Rapids, Mi
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    Quote Originally Posted by Randy S. View Post
    I also recommend installing a service valve in place of the drain plug. It will come in so handy for things like sampling or adjusting the level. This would be a good teaching point on oil management and the various conditions that cause the oil to take off out into the system.
    I am going to run a 45 off the outlet, and angle that down with a NPT to flare fitting so we can attach a copper line, or a hose to it for access. I plan on putting in a service valve as well. Seems like the easiest way to add access to it.
    Quote Originally Posted by Randy S. View Post
    Also bone up on the EPA regs regarding adding and or removing compressor oil.
    could you elaborate on this? i'm not aware of any regulations regarding removing oil? do you mean regulations regarding disposal?

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