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Thread: SIGHT GLASS

  1. #1
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    SIGHT GLASS

    I have several Carlyle O6D compressors and the oil level sight glasses have become clouded over and checking the level seems impossible. Is this a sign of a previous burnout? Running for extended periods of time with low oil level? Can these glasses be saved by cleaning or do I need to order replacements? Thank You Kirk

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  3. #3
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    Site Glass Clouding Issue

    Yes you can clean crankcase sight glasses. They should not get dirty but can become clouded or etched due to a previous burnout or an incomplete refrigerant oil changeout. Test the refrigerant and oil for any acid content. If the refirgerant has been changed you can get an oil test kit which can identify too much residual oil.

  4. #4
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    Could a guy get away with cleaning glass, changing oil, and just purging air from compressor? Or is a complete evacuation called for?

  5. #5
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    Proper procedure is to evacuate anytime after the refrigerant circuit is opened, which would include the compressor sump.

    If the sight glass is etched, you will have opened up the sump for naught. Get a new glass before you begin and you'll have 100% confidence that when you're done, the glass is clear.
    Building Physics Rule #1: Hot flows to cold.


    Building Physics Rule #2:
    Higher air pressure moves toward lower air pressure


    Building Physics Rule #3:
    Higher moisture concentration moves toward lower moisture concentration.

  6. #6
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    I would isolate the compressor and reclaim the gas. Test the oil for acid or contamination from oil mixes. Kits are off the shelf at most supply houses. Attempt to clean the sight glass, change if needed. Change the oil if needed and pull a vacuum on the compressor. Open valves and put the unit back in service.

  7. #7
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    Moved to Tech to Tech Commercial forum.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  8. #8
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    Quote Originally Posted by kaptnkirk View Post
    I have several Carlyle O6D compressors and the oil level sight glasses have become clouded over and checking the level seems impossible. Is this a sign of a previous burnout? Running for extended periods of time with low oil level? Can these glasses be saved by cleaning or do I need to order replacements? Thank You Kirk
    It ain't easy to take out. Take a chance to tab it off. Or buy a tool to open these glasses. I once tandem two of these together and it is a bitach

  9. #9
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    Shut the suction king valve while the compressor is running with gauges attached allowing it to shut off on low suction cut out. Immediately close off discharge king valve AFTER killing power to the unit.

    You wont have much left in the way of refrigerant.

    Acquire a tool to remove the sight glass. While you're at it take a oil sample and check for acid content. If acidic follow correct clean up procures to do a full clean up.

  10. #10
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    I have always been puzzled a little. I had a boss in Texas 30 yrs ago ask me what was taking me so long changing a TXV on a coffin case in a grocery store. Condensing units on the roof. I said I was in the process of Evacuating the system. He said why would I do that? He said refrigerant is heavier than air and no air could enter the system. Thus no evacuation needed. I have always evacuated systems after opening to the atmosphere. I no longer carry a vacumn pump and I am just a troubleshooter/ electrical fixer and sub out all refrigerant repairs. I was just curious as to wether a guy could pump out sump, drain oil, clean or replace glass, pump in fresh oil, and purge sump. Thanks I am eager to hear your responses.

  11. #11
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    Purging does not displace moisture. And if you're working with POE oils, you're dealing with an oil that is VERY hygroscopic (meaning it absorbs moisture ridiculously easily). Evacuation and fresh liquid line driers are your best defenses against moisture and contaminants.

    Worrying about air only is merely addressing a non-condensible problem...even there air contains moisture.
    Building Physics Rule #1: Hot flows to cold.


    Building Physics Rule #2:
    Higher air pressure moves toward lower air pressure


    Building Physics Rule #3:
    Higher moisture concentration moves toward lower moisture concentration.

  12. #12
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    Years ago this was fairly common. Valve out pull down to 3-5 psi make repair quickly and open valves. Thought being with some positive pressure pushin out nuttin could get in. Not acceptable practice since 92 but still done I'm sure.

  13. #13
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    Pull a plug out of a crankcase full of oil with even 1psig on it and you will quickly regret it.
    mikeacman

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