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  1. #1
    Join Date
    Jun 2010
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    74

    what are the proper charging and recovery procedures

    on water cooled and air cooled chillers ? do you just make sure you have flow thru the barrels too prevent the tubes from freezing when the pressure drops in the system ?

  2. #2
    Join Date
    May 2009
    Location
    Calgary AB
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    Well on a watercooled condenser you have a few options. You can drain both vessels and pushpull the gas out through the charging valve on the bottom of the condenser(typically) or the evaporator. In this situation you won't have to worry about freezing your vessel since you've eliminated the water from the system.

    You could also just pushpull the liquid out of the vessel or vessels until you're pulling vapor. Once you've started pulling vapor let the unit sit over night just incase you've got more liquid stuck up somewhere in the vessel. I know McQuays are notorious for having liquid traps inside the vessel so when you go to pull vapor off you run the risk of cracking your tubes. So best to let it sit over night and let the liquid boil off to vapor at it's own pace, once you're sure you've got all the liquid out start pulling the vapor out.

    Same methodology can be applied to air cooled. use your best judgement on which procedures work for your system. Reverse it for charging pushpull from your recovery tank to your vessel. Cheers.

  3. #3
    Join Date
    Dec 2012
    Location
    columbus, OH
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    2,028

    what are the proper charging and recovery procedures

    This was a question on the AC&R 410a safety test. The correct answer was charge as a vapor until saturation temp was slightly above 32* then charge as liquid.

  4. #4
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    Jun 2010
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    So just making sure you have flow through the barrel isn't the correct answer ?

  5. #5
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    Jun 2010
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    74
    So as long as you know there's no liq freon in the barrel your safe ? If just gas then u know your not boiling the freon causing the temp difference correct ? Just trying to wrap my head around this .

  6. #6
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    Jun 2010
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    74
    Quote Originally Posted by Core_d View Post
    This was a question on the AC&R 410a safety test. The correct answer was charge as a vapor until saturation temp was slightly above 32* then charge as liquid.
    What if it's a blended refrigerant and have to charge it as liq. ?

  7. #7
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    Dec 2012
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    columbus, OH
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    Quote Originally Posted by newbe0507 View Post
    What if it's a blended refrigerant and have to charge it as liq. ?
    I would say don't do it with a blend other than 410a.

  8. #8
    Join Date
    May 2009
    Location
    Calgary AB
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    Quote Originally Posted by Core_d View Post
    This was a question on the AC&R 410a safety test. The correct answer was charge as a vapor until saturation temp was slightly above 32* then charge as liquid.
    Oh I didn't realize this was a specific question from a test. I thought he was looking for generic information.

  9. #9
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    Dec 2012
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    columbus, OH
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    Quote Originally Posted by aaron604 View Post
    Oh I didn't realize this was a specific question from a test. I thought he was looking for generic information.
    Probably so but thats my 2 cents.

  10. #10
    Join Date
    Jan 2011
    Posts
    1,139
    Quote Originally Posted by aaron604
    In this situation you won't have to worry about freezing your vessel since you've eliminated the water from the system.
    I wanted to comment on this statement as it is patently false. If a chiller is drained without taking the heads off an getting all the water out of the tubes the possibility still exists for freeze bulging and potentially bursting a tube.

    One of the principles of the First Law of Thermodynamics is that the flow of heat is from hot to cold. I am stating this hypothetically, however, I have actually seen this occur. If there is residual water laying inside a tube and that tube is submersed in liquid refrigerant when the recovery of refrigerant gas begins the potential of freezing and bulging or bursting that tube is possible. As the pressure in the vessel drops below freezing the water laying in the tube starts to freeze. The rest of the water in the tube that sits outside where the refrigerant envelops the tube starts moving toward the cold area. (Remember hot flows to cold.) The ice ball continues to grow and there is enough water in a tube (even after it's "drained") to form an ice ball big enough to bulge or burst the tube.

    I will also state that there are many here who could remove all the charge from a flooded chiller with water in the machine without pumps running and not be at risk of freezing water in a tube. If one understands the prinicple and has a pressure/temperature chart for the refrigerant being recovered it isn't that difficult. I'm not saying this is how it should be done, but it can be done. Running water through the tubes while recovering vapor helps speed the process and is always recommended.

  11. #11
    Join Date
    Aug 2009
    Location
    Prattville, Alabama
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    2,020
    I also worry about a restricted tube holding water. Or a slug of mud freezing. Or an incorrectly plugged tube holding water. Basically, I just anticipate the worst possible condition that the tubes can be in.

  12. #12
    Join Date
    Jan 2011
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    Quote Originally Posted by Nuclrchiller View Post
    I also worry about a restricted tube holding water. Or a slug of mud freezing. Or an incorrectly plugged tube holding water. Basically, I just anticipate the worst possible condition that the tubes can be in.
    Excellent points.

  13. #13
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    Jul 2012
    Location
    Western KY
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    Quote Originally Posted by Nuclrchiller View Post
    I also worry about a restricted tube holding water. Or a slug of mud freezing. Or an incorrectly plugged tube holding water. Basically, I just anticipate the worst possible condition that the tubes can be in.
    Beat me to the plugged tubes issue. Unless it is impossible always keep flow while recovering. Obvious reasons, as already pointed out, for this. No reason not too.

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