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  1. #1
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    Sporlan Tex failure?

    This is only the second time I have come across this, a tex valve that just dumps liquid thru the external equalizer into the suction, not into the evap. Enough to ice the equalizer line and cycle the compressor, but not flood it out. This was an SQ valve, pc head, "A" cartridge, but I think the last one was just a regular "G" body medium temp.
    Any ideas why it could fail this way?

  2. #2
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    The clearance between the pushrod and the pushrod hole is a factory defined specification. Leakage around the pushrods is one of the many checks that are made on a TEV before it is considered passable, and ready for sale.

    It is the tight clearance between the pushrod and pushrod hole that prevents liquid refrigerant, flowing from the valve's inlet port to the valve's pin/port, from leaking out through the pushrod holes and onto the equalizer connection (and onto the suction line).

    The first valve below is a standard TEV (non balanced ported). There are two pushrods, although in the view you can only see one. Imagine that the pushrod is loose...sloppy loose...in the pushrod hole. Liquid would pore through the clearance between the pushrod and pushrod hole, leaking out the external equalizer fitting and onto the suction line.

    The next photo is a Balanced Q valve. This is a single pushrod, and there's a seal around the pushrod (preventing the refrigerant from leaking out to the external equalizer fitting. If that seal is defective, or has been damaged, it will allow refrigerant to leak out to the external equalizer fitting.

    Now, if for some reason the pushrods in your valve had been replaced with pushrods from another valve, the new pushrods might have a different diameter, causing the clearance to be greater (and allow leakage).
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  4. #3
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    Thread Starter
    Thanks

  5. #4
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    Quote Originally Posted by bunny View Post
    The clearance between the pushrod and the pushrod hole is a factory defined specification. Leakage around the pushrods is one of the many checks that are made on a TEV before it is considered passable, and ready for sale.

    It is the tight clearance between the pushrod and pushrod hole that prevents liquid refrigerant, flowing from the valve's inlet port to the valve's pin/port, from leaking out through the pushrod holes and onto the equalizer connection (and onto the suction line).

    The first valve below is a standard TEV (non balanced ported). There are two pushrods, although in the view you can only see one. Imagine that the pushrod is loose...sloppy loose...in the pushrod hole. Liquid would pore through the clearance between the pushrod and pushrod hole, leaking out the external equalizer fitting and onto the suction line.

    The next photo is a Balanced Q valve. This is a single pushrod, and there's a seal around the pushrod (preventing the refrigerant from leaking out to the external equalizer fitting. If that seal is defective, or has been damaged, it will allow refrigerant to leak out to the external equalizer fitting.

    Now, if for some reason the pushrods in your valve had been replaced with pushrods from another valve, the new pushrods might have a different diameter, causing the clearance to be greater (and allow leakage).
    Thanks for that explanation. I had one last year. First one I've seen. I didnt know why it was happening but now I do!

    Sent from my SM-G930V using Tapatalk

  6. #5
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    I think bunny suspect the pushrods may have been changed is because an Q-series valve isn't likely to be old enough to have worn out like that.

    The only Sporlan valves I ever found blowing by the rods and down the equalizer like this with were 30 years old or more.

    TEV bodies rarely fail, but the tech often fails to find the real reason for the problem. He may fix it by changing out the whole valve, when a thermostatic element or a plugged inlet screen was actually the culprit.

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  7. #6
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    It was actually an SBQ in a 4 ft self-contained produce merchandiser, I didn't take the serial number but it couldn't have been more than 3 years old.
    The apprentice I was with took the old one apart, said he felt a roughness in the motion of the pushrod. I guess we could have just changed the cartridge, but he needed the brazing practice.
    M4F0075-cav-212 is the typical condensing unit for these cases.

  8. #7
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    SBQ is a more interesting scenario. The balanced ported valves have a single pushrod, with a seal around it. If the seal gets damaged, you'll likely have some leakage.

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