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  1. #1

    inverted trap on top of suction risers

    Good evening to everyone.
    I`m quite familiar with the use and purpose of oil traps at the bottom of suction risers, and every other 15 feet, in order to make sure the oil returns to the compressor. What I did not know was that at the TOP of the suction risers, I should install an inverted "p"trap. I just saw this in the photographs of the installation of a walk-in that appear in a website. Is that correct? If so, what should be the purpose of it? Thank you for any explanation.

  2. #2
    Join Date
    Mar 2010
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    Morgan Hill Ca.
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    Quote Originally Posted by coldseeker2012 View Post
    Good evening to everyone.
    I`m quite familiar with the use and purpose of oil traps at the bottom of suction risers, and every other 15 feet, in order to make sure the oil returns to the compressor. What I did not know was that at the TOP of the suction risers, I should install an inverted "p"trap. I just saw this in the photographs of the installation of a walk-in that appear in a website. Is that correct? If so, what should be the purpose of it? Thank you for any explanation.
    Virtually serves the same purpose as the traps on the way up, it keeps the oil and or liquid refrigerant from running out of the horizontal run back to the evaporator...
    If a day goes by and you have learned nothing, I hope you got a lot of sleep.

  3. #3
    Join Date
    Dec 2000
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    Flat Rock, NC
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    463
    I always slope my lines towards comp. and don't use inverted traps at top of risers. If you cannot doe thus then yes I would do the riser w/ inverted trap.

  4. #4
    Join Date
    Mar 2003
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    Cochrane, AB
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    Inverted traps are for suction lines dumping into a header or common suction line. Single lines do not require an inverted trap.

  5. #5

    Be careful

    APC

  6. #6

    Be careful

    APC require it on some of their unit

  7. #7
    Join Date
    Mar 2010
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    Morgan Hill Ca.
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    Quote Originally Posted by mspanky View Post
    Inverted traps are for suction lines dumping into a header or common suction line. Single lines do not require an inverted trap.
    As for the "not required" part of this......I call B.S. . Depends on the system and component requirements... Especially larger systems with huge oil capacities...
    If a day goes by and you have learned nothing, I hope you got a lot of sleep.

  8. #8
    Join Date
    Mar 2003
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    Cochrane, AB
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    I stand by my statement if the suction is sloped towards the compressor in the slightest amount. If anyone has any specific situations where this is not true, lets hear them. (I haven't seen every type of install possible, obviously.)

  9. #9
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    Mar 2010
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    Morgan Hill Ca.
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    Quote Originally Posted by mspanky View Post
    I stand by my statement if the suction is sloped towards the compressor in the slightest amount. If anyone has any specific situations where this is not true, lets hear them. (I haven't seen every type of install possible, obviously.)

    I can tell you that if you had a system with the compressor/condenser at the roof and an evaporator several floors below, it is imperative that you inverted trap the suction piping if the system is equipped with a hot gas bypass capacity control scheme. I am sure sloping the piping on the roof will help, but will not ensure oil slug protection upon bypassing...
    If a day goes by and you have learned nothing, I hope you got a lot of sleep.

  10. #10
    Join Date
    Feb 2008
    Location
    California
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    You could use an inverted suction trap if the evaporator is above the compressor. It would keep liquid refrigerant and oil in the evaporator, instead of falling down the suction line in the off cycle.

    You could also use an inverted suction trap on the larger diameter riser of a double suction riser. The inverted trap prevents returning oil from the smaller diameter riser from falling back down the larger diameter riser during times of reduced capacity.

  11. #11
    Good evening to all. Talking about P traps at the top of risers: if it were a discharge line riser instead of a suction line riser, with the piping going, immediately after the riser, to the remote condenser inlet connection: the P trap at the top of the riser would prevent oil and liquid from falling back to the compressor, as well as creating a place for non-condensable purging, right? Could such a trap be used instead of a check valve?

  12. #12
    Join Date
    Jan 2006
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    DFW Metroplex
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    4,910
    Quote Originally Posted by coldseeker2012 View Post
    Good evening to all. Talking about P traps at the top of risers: if it were a discharge line riser instead of a suction line riser, with the piping going, immediately after the riser, to the remote condenser inlet connection: the P trap at the top of the riser would prevent oil and liquid from falling back to the compressor, as well as creating a place for non-condensable purging, right? Could such a trap be used instead of a check valve?
    It sounds to me like based on your post that you have an understanding that migration of oil and liquid are both a major concern and can create serious problems if not addressed.

    So let's think this through a little bit....

    What is the purpose of a trap in a refrigeration system?

    What is the purpose of a check valve in a refrigeration system?

    Can a trap be used in place of a check valve in a refrigeration system and still achieve the desired results?

    I'm not trying to hang you out, coldseeker2012 - but rather I think you bring up a very valid question which warrants further discussion.
    "The problem is the average person isnt tuned in to lifelong learning, or going to seminars and so forth. If the information is not on television, and its not in the movies they watch, and its not in the few books that they buy, they dont get it" - Jack Canfield

  13. #13
    Join Date
    Feb 2007
    Location
    Georgia
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    162
    The Trane Recipracating Manual and Copeland Compreesor Manual part 4 give excellent guidance on piping design.

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