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Thread: Ruptured Filter Driers

  1. #1
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    Ruptured Filter Driers

    I have a facility which has several AAON RTUs . The refrigerant is R410a . The past month two ( 2 ) liquid line filter driers have ruptured . One was OEM installed Sporlan and the other ( ALCO / Emerson ) was field installed by others due to compressor replacement by others. Has anyone else seen liquid line driers explode ? These RTUS are part of the package ; have to take these AAONS on as part of the contract . I was called in last night because a drier failed and released the refrigerant . There was 27 pieces of fire equipment on site when I arrived . It is a 1.2 million sq ft facility . Apparatus from neighboring counties plus everything from local county .
    Last edited by CHILLERSVCMAN; 09-26-2020 at 10:54 PM. Reason: more info

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    Quote Originally Posted by CHILLERSVCMAN View Post
    I have a facility which has several AAON RTUs . The refrigerant is R410a . The past month two ( 2 ) liquid line filter driers have ruptured . One was OEM installed Sporlan and the other ( ALCO / Emerson ) was field installed by others due to compressor replacement by others. Has anyone else seen liquid line driers explode ? These RTUS are part of the package ; have to take these AAONS on as part of the contract . I was called in last night because a drier failed and released the refrigerant . There was 27 pieces of fire equipment on site when I arrived . It is a 1.2 million sq ft facility . Apparatus from neighboring counties plus everything from local county .
    That sounds crazy and I would love to find out what caused the failure but I think you are in the wrong thread.

    Sent from the Okie state usin Tapatalk

  3. #3
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    No relief valves? Filter driers rated 650#, rupture 2.5x?
    Controls fail safe?

  4. #4
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    Thread Starter
    I am
    LONG DAY / NIGHT

  5. #5
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    None that I have seen . Need to give it 100% evaluation . It was dark and had to deal with the media / TV crews ! " NO COMMENT " as they have my chariot in background

  6. #6
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    I find it hard to imagine that a steel shell liquid line filter-drier would fail before the annealed copper joints which are everywhere else in the system. And that would require about 1800 lbs. pressure. I would think the compressor would stall or overload well before it generated anything like 1800 lbs.

    What exactly failed about the driers? Did the shell rupture outwards? Did the welds fail? Are the female tubing stubs dislocated at the ends?

    Were both failures in one unit? Or were the drier failures in different units?

    Do these units have high pressure controls? And if so; are they tested / known good?

    Have the compressor contactors been replaced?

    PHM
    --------


    Quote Originally Posted by CHILLERSVCMAN View Post
    I have a facility which has several AAON RTUs . The refrigerant is R410a . The past month two ( 2 ) liquid line filter driers have ruptured . One was OEM installed Sporlan and the other ( ALCO / Emerson ) was field installed by others due to compressor replacement by others. Has anyone else seen liquid line driers explode ? These RTUS are part of the package ; have to take these AAONS on as part of the contract . I was called in last night because a drier failed and released the refrigerant . There was 27 pieces of fire equipment on site when I arrived . It is a 1.2 million sq ft facility . Apparatus from neighboring counties plus everything from local county .
    PHM
    --------
    The conventional view serves to protect us from the painful job of Thinking

  7. #7
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    Code interpretation changed a few years back on air cooled relief valve requirements, something about the system volume and condenser design I think. Tested the “new” thin wall cu tube condensers and the thin tube exposed at the end sheet consistently failed ~2100# .
    Check the filter driers are rated for R410a, the larger capacity components were slow getting to market and R-22 rated filter driers may have been used.
    Check head pressure controls, welded compressor contactors.
    Does circuit have pumpdown? What is the pumpdown capacity? Overcharge can cause hydrostatic failure.
    Found Aaon units with compressor contactors chattering due to air flow sensors. Can cause welded contactor.

  8. #8
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    Made this its own thread.
    Contractor locator map

    How-to-apply-for-Professional

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

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  10. #9
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    The only time I've dealt with components exploding was a Mitsubishi multi city. One of the check valves exploded. They said it was due to internal wear from low load operation.

    I would also make sure they are rated for 410.

    I would also look at the refrigerant piping, and see if a failed reheat valve or other component could have failed and caused the liquid side to over pressurize.

    Don't the aaons have the thermal/pressure reliefs on the piping?

  11. #10
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    The only time I have seen this is when liquid refrigerant gets trapped and then expands with temp rise..
    "He who knows the least, knows it the loudest"
    I'm not young enough, to know everything...

  12. #11
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    Not all parts are compatible with R410a pressures. I would confirm that first.

    Is there a check valve followed by a LLSV or other similar scenario that may have allowed hydrostatic expansion to overcome the rated pressure?
    Quickly, I must hurry, for there go my people and I am their leader!

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  14. #12
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    I agree with looking into liquid locked piping. That causes an exponential pressure rise with temperature rise.

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    Quote Originally Posted by ehsx View Post
    Check the filter driers are rated for R410a, the larger capacity components were slow getting to market and R-22 rated.
    While this is a valid point, manufacturers usually have about a 4 to 1 safety factor built into their products, so if the drier is rated at 400 psig working pressure, it shouldn't burst until at least 1600 psig, which is significant. Now a 410A rated drier would likely have a burst pressure of over 2600 psig.

    I would agree with PHM that normally something else in the piping would fail first before a drier shell, unless they are have a specific hydrostatic issue with liquid changing to gas within a small section near the drier and no control safeties are going to recognize that and shut anything down.


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  17. #14
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    Only time I see a drier fail is by rust.

    Sent from my Moto Z (2) using Tapatalk

  18. #15
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    Thanks for the feed back everyone . One drier came apart at the end weld - perfect separation. the other had the casing blow out just about dead center . High pressure switches verified and functional.The driers do not state 410a . Again one was OEM Sporlan and the other was field installed Alco / Emerson when compressor was changed by others .

  19. #16
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    No liquid line solenoids . However there is a diverting valve in the discharge line to bypass the condenser to go to reheat coil during dehumidification

  20. #17
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    No welded contactors . No pump down in use on these units . This could get interesting as there 34 of these systems with 4 circuits each . Equipment is approx 9 - 10 years old . I have already had the comment thrown at me " How has it lasted this long ? " with the strange head tilt .

  21. #18
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    Quote Originally Posted by CHILLERSVCMAN View Post
    No liquid line solenoids . However there is a diverting valve in the discharge line to bypass the condenser to go to reheat coil during dehumidification
    Check the approach of the reheat coil and subcooling off the reheat coil. Air flow and interlocks. Switch and check mode xtions and operation. Is/are there a check valve(s) in the ll?
    Or any potentials for liquid lock ?

  22. #19
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    One drier ( Sporlan OEM ) failed at the end weld - perfect separation - looked like it could have been cut with a band saw . The other drier was an Alco / Emerson ( field installed when compressor was replaced by others ) which ruptured just about dead center. This involved two different units - 1 was VAV serving office the other was constant volume serving production . All units on site operate 24 /7 . They also have VFDs on supply fans set to 55hz ( vav maintains 1.75" SP ) High pressure switches were tested with a gauge and controlled nitrogen . Some of the compressor contactors have been replaced . Condenser fan cycling pressure switch operation has been verified . Many of the condenser fan contactors have been replaced by me due to wear.

  23. #20
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    There is no check valve in liquid line that I have seen yet . Airflow readings are very close to design / start-up reports .

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