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  1. #1
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    With or without external equalizer



    TXV comes in two main features, with external equalizer and with internal equalizer.
    Both have the same capacity and working pressure.

    My question is: Would it make any difference in use, regarding capacity, type of evaporator, whit refrigerant distributor after the TXV or without one.

    Go ahead gentlemen.



  2. #2
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    Re: With or without external equalizer

    My understanding is,

    If pressure at evaporator outlet is nearly the same as the inlet, then an internal valve will do.

    If the pressure at the evaporator outlet is much lower than the inlet (long coil or distributor) then an external valve is the one to use.

    Or you can fit external valves in either case, the equalising line must be connected near the evap outlet, though i don't beleive it makes any differenc if its before or after where the phial is fitted. It must not be just capped off as i have seen done!

    Jon
    Mostly found in Oxfordshire, UK :)

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    Re: With or without external equalizer

    Obviously didn't write this myself ,To lazy.

    Q: What is the difference between an internally or externally equalized Thermostatic Expansion Valve?
    An internally equalized Thermostatic Expansion Valve uses the input pressure from the evaporator to create the working pressure in the valve. An externally equalized valve uses the output pressure from the evaporator, compensating the pressure drop through the evaporator, for the same purpose.If an internal equalization valve is used in a system with a great pressure drop through the evaporator, the pressure below the diaphragm will be greater, causing the valve to enter a more limited opening position and resulting in greater overheating than desired (lack of gas).
    Q: When should I use external equalizer in the Thermostatic Expansion Valve ?
    1. In any large system, usually with capacity of more than 1 ton
    2. In any system using a distributor
    Note: For field replacement, you can always replace an internally equalized valve by an externally equalized valve, but you must never replace an externally equalized valve by an internally equalized valve.
    Q: If I need to replace an internally equalized valve and all those available are externally equalized valves, can I just “plug” the equalizer connection?
    No, the equalizer must be connected to the suction line in the bulb. Plugging the equalizer connection will prevent the valve from functioning properly.
    Q: Will an externally equalized Thermostatic Expansion Valve allow the system pressures to be equalized during the off cycles?
    No, an externally equalized valve will not allow the increase and decrease side of the system to be equalized during the off cycle. The only way of doing this is through use of a Thermostatic Expansion Valve.
    Q: Where should the external equalizer be installed?
    The external equalizer line must be installed at the top of the suction line, before any siphon and located 15 cm from the bulb position. If this is not possible, and a different location is required, one must first confirm if the pressure in the location desired is identical to the pressure at the bulb height.
    Q: What happens if the equalizer tube is dented?
    If the equalization line is folded, the pressure felt in the lower part of the diaphragm will no longer correspond to the output pressure of the evaporator and the valve will be unable to function as intended.
    Q: I saw some “frozen” equalizer tubes. Is this normal?
    Freezing in the equalizer line is an indication that the packing ring of the needle leaks and allows the refrigerant’s pressure to leak and expand in the equalizer tube. Depending on the type of valve, or the assembly, the entire valve must be replaced.

    Cheers
    Stu
    Tool's ? check ! Condom's ? check !
    If you can't fix it , f*ck it !!!

  4. #4
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    Re: With or without external equalizer

    Slighly off topic but isn't the reason for having the equaliser line before the phial because if the TEV was to leak inernally through the equalising pipe it would go unchecked to the compressor.

    If the line is before the phial then the TEV has a chance to close down? Can't see that this will stop the floodback - just means the food defrosts and the compressor packs up I suppose...

    Cheers,
    Andy.
    Health and safety first..........unless I'm in a hurry.

  5. #5
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    Re: With or without external equalizer

    I think the destructions say to put it after the phial so it would go unoticed, have only seen this once, frost back to comp and no ice in the water jacket!
    Mostly found in Oxfordshire, UK :)

  6. #6
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    Re: With or without external equalizer

    Oh yes.

    Muppet.
    Health and safety first..........unless I'm in a hurry.

  7. #7
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    Re: With or without external equalizer

    Quote Originally Posted by Tayters View Post
    Oh yes.

    Muppet.
    I have to read the box every time i fit one as i never remeber all the info!
    Mostly found in Oxfordshire, UK :)

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    Re: With or without external equalizer

    again off to the side,some valves danfoss with the replaceable orifice you can clip the lid of the orifice box with the number of the orifice went to change one the other day the ;lid; clipped to the valve read number 2 but the one in the valve was a 3 just as well i carry plenty of them,people who dont give a toss annoy me!

  9. #9
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    Re: With or without external equalizer

    Been caught out with that one on a couple of occasions ,P!ssed me off no end!!
    Cheers
    Stu
    Quote Originally Posted by cadwaladr View Post
    again off to the side,some valves danfoss with the replaceable orifice you can clip the lid of the orifice box with the number of the orifice went to change one the other day the ;lid; clipped to the valve read number 2 but the one in the valve was a 3 just as well i carry plenty of them,people who dont give a toss annoy me!
    Tool's ? check ! Condom's ? check !
    If you can't fix it , f*ck it !!!

  10. #10
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    Re: With or without external equalizer

    hey Stu, where is the paper from?
    can you give me the link/

  11. #11
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    Re: With or without external equalizer

    I'll have a look Chemi , not sure where I pulled that one from.
    Cheers
    Stu
    Tool's ? check ! Condom's ? check !
    If you can't fix it , f*ck it !!!

  12. #12
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    Re: With or without external equalizer

    Here you are my friend.
    Some other good stuff on it too.
    Just as well I didn't claim to have written it .

    http://www.mipal.com.br/usa/dicas/dicas.php?dica=12

    C
    heers
    Stu
    Last edited by stufus; 07-02-2012 at 08:15 PM.
    Tool's ? check ! Condom's ? check !
    If you can't fix it , f*ck it !!!

  13. #13
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    Re: With or without external equalizer

    Quote Originally Posted by cadwaladr View Post
    again off to the side,some valves danfoss with the replaceable orifice you can clip the lid of the orifice box with the number of the orifice went to change one the other day the ;lid; clipped to the valve read number 2 but the one in the valve was a 3 just as well i carry plenty of them,people who dont give a toss annoy me!
    Yep, carry many sizes, too far to run to suppliers. Write the size number on evaporator so it's easy to see. Notice how you need a microscope to read new Danfoss orifice number. Can take for granted what the red lid says, but to be sure...
    To the optimist, the glass is half full. To the pessimist, the glass is half empty.

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