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  1. #1
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    Torn screens in core drier shells w/410a

    Does anyone else keep a few new screens on their truck??? I seem to find a lot of blown out screens on the 410 a machines reguardless of who made the equipment. I have decided to start keeping a pile of new ones on my truck... Anyone else notice this??
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  2. #2
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    I don't think it's specific to 410, I noticed a few torn screens this summer. One was on a 507 chiller, another was an older 22 system, but the FD was relatively new.
    "If you call that hard work, a koala’s life would look heroic."

  3. #3
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    I too have seen torn screens on equipment operating on other refrigerants. The observation I was trying to highlight was that on the higher pressure systems ( like 410 ), I am seeing a higher instance of torn screens than I have seen on other systems using other refrigerants. It would be my guess based on what I am seeing, That a 410 machine with a clogged screen would be more likely to tear and release trash into the EXV than a clogged screen on a 134 system. Especially if the condenser coil is a micro-channel coil. The clogged screen basicly causes the circuit to try to pump down, increasing the P/D across the screen until it fails.............................. I have seen instances where the torn screen had beed cleaned and reinstalled simply because someone " had no other option" but to get the equipment back on line and did not cary replacement screens for whatever reason. If you service equipment that uses core driers, I feel you owe it to your customer to have a replacement screen available if the need ever arises..............

  4. #4
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    I agree, I still don't carry any, but the 2 chillers that had torn screens now have a couple extra screens laying on the extra cores they keep on hand.

    Makes sense that they would tear easier, I'm not a basher of 410, but it's another negative of this style of refrigerant.
    "If you call that hard work, a koala’s life would look heroic."

  5. #5
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    Thanks for posting the pictures,they remind me i need to go back to school to get into another line of work like truck driving or clown college.

  6. #6
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    that looks like danfoss internals i had a ripped one a few weeks ago it was on a carrier scroll chiller they used a 1 core dryer on a 100 ton circuit.

  7. #7
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    Quote Originally Posted by under pressure View Post
    ...It would be my guess based on what I am seeing, That a 410 machine with a clogged screen would be more likely to tear and release trash into the EXV than a clogged screen on a 134 system. Especially if the condenser coil is a micro-channel coil. The clogged screen basicly causes the circuit to try to pump down, increasing the P/D across the screen until it fails...
    why is it clogged? a clogged screen, no matter the refrigerant, will cause a failure of this type eventually.

    why do you see 410a being worse? i don't know. other than the canister is undersized and the screen is seeing a higher pressure drop when clean to begin with.
    "Mother" is the name for God on the lips and hearts of children....The Crow

  8. #8
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    I'm not a drier expert, but I believe most if not all driers of this style are all the same diameter and run basically the same guts in them, the only variable is how many cores you can stack in there.

    I'm not sure if the velocity is any faster in a 410 system vs a 22 system (or what ever system you're running), but perhaps with the higher pressures it's moving a bit faster which would cause more force against the screen and blow the screen out.

    Just my guess
    "If you call that hard work, a koala’s life would look heroic."

  9. #9
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    Switch to a tube type screen has much more surface. Sporlan makes it and fits in Alco shell. Mcquay rec. changing all screens that are Alco shells on our screw machines.

  10. #10
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    Quote Originally Posted by jayguy View Post
    why is it clogged? a clogged screen, no matter the refrigerant, will cause a failure of this type eventually.

    why do you see 410a being worse? i don't know. other than the canister is undersized and the screen is seeing a higher pressure drop when clean to begin with.




    Are you Serious??????
    It's All about Heat.............................to a degree

  11. #11
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    Quote Originally Posted by under pressure View Post
    Are you Serious??????
    i was asking a question rather than making a statement about the under sized canister. i do not know what size equipment you are working on. it appears that you only have a single core shell in the picture but i could be wrong there.

    most manufacturers are going to undersize the F/D because they can (new tubing, virgin refrigerant, etc.). but after a failure, the same size F/D is going to be undersized for the application.

    again, not enough information for me to make a judgment so i am asking questions with the '?'....clear as mud now?
    "Mother" is the name for God on the lips and hearts of children....The Crow

  12. #12
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    Quote Originally Posted by under pressure View Post
    Does anyone else keep a few new screens on their truck??? I seem to find a lot of blown out screens on the 410 a machines reguardless of who made the equipment. I have decided to start keeping a pile of new ones on my truck... Anyone else notice this??



    I'll quote My origional post to restate my Observation.

    I have seen a crapload of failed screens on 410 chillers with micro channel coils. I belive the normal high operating pressures of 410 against a clogged peice of window screen would cause the screen to fail sooner than say a 134 system with a tube and fin condenser. The micro channel coil will not hold the refrigerant charge of the machine and the restriction will keep the machine in a state of trying to pump down untill the high pressure control takes the machine down, or the screen blows out and is no longer causing a restriction.
    My only reason for posting this was to suggest that if you service this kind of equipment, CONSIDER throwing a couple screens on the shelve next to those drier cores that are rolling around. What would you do REALLY, if you were forced to decide weather to reassemble a core drier with a blown out screen after a long day and a couple more calls you need to catch before the day is over???????????/ I know what I would be tempted to do, but then........I cary some screens with me... Thats all I was trying to say. ( now where did i park that Clown-Car??????????? )
    It's All about Heat.............................to a degree

  13. #13
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    I suspect, it has something to do with the mesh width and surface. We use a system that has a mesh column inside which provides far higher surface and hence less pressure drop. The picture is taken from the Danfoss website.
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