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  1. #1
    Join Date
    Nov 2011
    Location
    South Texas
    Posts
    60

    RTAA 215 possibly sucked oil charge out of oil cooler after pulling vaccum.

    I had a call out late yesterday afternoon found 1 circuit completely flat tube rubbed at condenser tube sheet and dropped complete charge and it was raining all day. Welded it up put 2 new drier cores in her and nitrogen purged it then started vacuum pumps

    Energized load/unload and master oil solenoid to pull a vacuum. I used 2 pumps both large 7 or 9 cfm refcos I used one at the compressor on high and low side with micron gauge on low side, and installed the other on the liquid line above the drier shell started and pulled a 14 hour vacuum on it.

    It pulled down to 500 microns so shut the pumps down and isolated the system and left to come back later and see how it was holding. Came back at 1 this evening and it had come up to 1175 microns after sitting for 5 hours.
    Decided I was going to bring it up to 5-10 psi using dry nitrogen and let it sit overnight so the nitrogen could grab some more moisture out of it then start another vacuum monday morning.

    Here's where it gets interesting I have a theory of what happened but want some of your opinions and what I need to do to safely start it back up. I haven't had this happen before. I did forget to de energize the load/unload and master oil solenoid if that's what caused this.

    I set my nitrogen regulator on 30 psi and began introducing slowly into the discharge line side of the compressor only. I was watching my gauge above the drier shell and was trying to get it to about 15 lbs to leave it overnight. It was almost out of the vacuum and into positive pressure above the drier shell when I began hearing a gurgling sound inside the condenser above the compressor the gurgling then continued to get louder and I began to hear it sound almost like water running inside the condenser down into the compressor and then into the suction line heading to the chiller barrel. At that point I remembered I forgot to de-energize the load unload and master oil solenoids and then killed them and turned off the nitrogen. Then just listened and watched and waited and the noise got less and less and my pressures slowly equalized at 15 psi at the discharge line on the compressor and above the drier shell at the service port after about 5 minutes. When I disconnected my gauges at the suction line on the compressor I had a steady stream of oil come out of my service hoses.

    It's my theory that somehow due to pressure being applied on the discharge and a vacuum still existing on the condenser it sucked the oil cooler dry once a siphon action started. What would need to be done to safely start this circuit back up if it did actually suck the oil cooler out into the system. Any of you have other ideas as to what could have happened.

    Sorry to be so long winded but I wanted to give a blow by blow so others could offer ideas and suggestions. Flame suit on if I made a idiot mistake.

  2. #2
    Join Date
    Dec 2010
    Location
    Down by the river
    Posts
    1,579
    As long as you have the propper level of oil in the oil separator your good, or is that what you are calling an oil cooler?

  3. #3
    Join Date
    Nov 2011
    Location
    South Texas
    Posts
    60
    You are correct i think it emptied the oil separator. Im heading over in a bit to see how vacuum is doing. Then im going to get some pressure in it and verify oil separator level. Thanks

  4. #4
    Join Date
    Mar 2004
    Location
    ottawa canada
    Posts
    1,848
    You should have checked the separator level when she was flat out of gas . Its a whole lot quicker and easier than if its in a vacuum or under pressure .
    The 64 roars to life Whoo hoo ...shes a rolling chassis .
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    I"m not a service tech.. I"m a thermodynamic transfer analyst & strategic system sustainability specialist
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  5. #5
    Join Date
    Nov 2011
    Location
    South Texas
    Posts
    60
    Brought system to atmosphere using nitrogen and checked oil using sightglass method. From the centerline of the oil separator at the very bottom i have a oil level that is sitting at about 3 to 3.5 inches It is exactly 2 3/4 inches below tranes recommended minimum level. There appears to be a solid column of oil in the suction line at least as high as the service port on the end of the compressor. Based off of the above what can be done to safely restart this system without fragging a compressor. Thanks for the help

  6. #6
    Join Date
    Aug 2006
    Location
    Mixing oil and fire with a big spoon.
    Posts
    4,008
    i wouldn't be worried about the oil level...it will come back pretty quick as long as it was in there to begin with...i would be more worried about the (potential) water in the system sitting UNDER the oil. see attached picture. trane oil 15 on top, bottled water on the bottom, 454 micron vacuum on top of the oil...no water boiling at 72.3F water temperature.
    Oil over Water Evacuation Experiment 001.jpg
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  7. #7
    Join Date
    Nov 2011
    Location
    South Texas
    Posts
    60
    The oil was definitely there to begin with the oil level was was at trane's recommended nominal level 2 months ago when we did the quarterly pm. But because the master oil solenoid was on when my goofy once in a lifetime situation occurred the compressor and suction line are full to the top with the almost complete 8 gallons of oil that was originally in the separator there is only about 3 to 3.5 inches of oil level in the separator.

    Do you think it safe to carefully nudge the compressor using the contactor to clear the rotors and suction line with that much oil in it? With that little oil in the separator if the compressor could safely start should the oil return quick enough to keep compressor in a safe operating level.

    Or do I need to just plan on pulling the suction and discharge endbells to drain as much oil as possible from the compressor and suction line before even attempting to start it. Then refill the separator and start it up and monitor and adjust oil levels as necessary

    I'm trying to figure out if I'm being correct in being this cautious or just flat paranoid and it's a simple put gas in her nudge the compressor and light her off and she will find her own happy spot and level out and I am making it way more complicated than it needs to be.

    Thanks again for all of the help I've just never had this happen before and neither has my grandpa who just retired last year at 90 years old from the HVAC field. He can't help me much on screw chillers because at the time we just didn't have that many around the area to work with most were the old semi hermetics we worked with.

  8. #8
    Join Date
    Dec 2010
    Location
    Down by the river
    Posts
    1,579
    If oil is in suction your fine, use compressor test mode to do initial start. That oil will be back in place. You are fine.

  9. #9
    Join Date
    Dec 2010
    Location
    Down by the river
    Posts
    1,579
    You are being to cautious, which is good. You have a level in the separator, you are protected.

    Run it for 10 min and recheck oil

  10. #10
    Join Date
    Nov 2011
    Location
    South Texas
    Posts
    60
    10-4 I will definitely sleep better tonight for sure. I left a holding charge in it overnight tomorrow I will go ahead and start a vacuum again and if everything checks ok micron wise this time I'll go ahead and kick the tires and light the fire and say a few little prayers over it. A simple job turned into a major pain. A few weeks ago I had temp sensors conk on the other circuit.

  11. #11
    Join Date
    Nov 2011
    Location
    South Texas
    Posts
    60
    Got rained out tuesday. Purged nitrogen and started vacuum pumps again this afternoon If my micron gauge has good results. Should be able to charge it and celebrate. Then go hop on a cruise ship for a week starting saturday and forget all the headaches of the last month
    Thanks for all the help

  12. #12
    Join Date
    Nov 2011
    Location
    South Texas
    Posts
    60
    She's back in business and running and running perfect so far knock on wood. It took a few hours to get the whole charge into it and get her all leveled back out but so far so good. Thanks for all of the help and reassurance as to my oiling problem I lost a decent amount of sleep over it the last few evenings.

  13. #13
    Join Date
    Dec 2010
    Location
    Down by the river
    Posts
    1,579
    As long as you have a decent level in the srparator, and you know the rest of the oil is in the circuit, do not fear. Worst case add a gal. Run and remove after some run time.

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