View Poll Results: What provides the seal? The Schrader valve or its cap?

Voters
173. You may not vote on this poll
  • The Schrader Valve.

    95 54.91%
  • The Service Port Cap.

    60 34.68%
  • Apple Juice.

    18 10.40%
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  1. #1
    Join Date
    Jul 2008
    Location
    In a van down by the river.
    Posts
    55

    Question Schrader Valve or Cap? What's the seal?

    What ultimately provides the seal?

    I'm talking about the common 1/4" service ports we connect our guages to. A member of another forum (Non HVAC&R related) called me out on what I believe to be true.

    So what's y'alls thoughts?

    When it comes to providing the actual sealing and containment of refrigerant within a given circuit at the schrader type service port, is it the valve core or the cap (that I keep finding laying on the floor of the compressor section )?

    I say it's the cap.


    While we're at it, if you believe it's the cap, what type do you prefer (and why)? Metal for its new metal-to-metal seal with each snugging or the metal/plastic with an O-ring?




    I'm a new member of these forums and just cut the cheese in the back of the room. Opps.

    Thanks folks.
    Last edited by BC847; 07-09-2008 at 11:36 PM.

  2. #2
    Join Date
    Apr 2007
    Location
    St.louis metro area
    Posts
    315
    The valve core only seals long enough so you can remove you gauges and put the cap on which actually seals it. Not saying it is going to leak, but it won't leak for sure if the cap is tightened down on it.

  3. #3
    Join Date
    Jul 2008
    Location
    In a van down by the river.
    Posts
    55
    Quote Originally Posted by Joe Cool View Post
    The valve core only seals long enough so you can remove you gauges and put the cap on which actually seals it. Not saying it is going to leak, but it won't leak for sure if the cap is tightened down on it.
    Yup (you're preaching to the choir).

  4. #4
    Join Date
    Feb 2005
    Location
    Barrie, Ontario
    Posts
    4,622
    Schrader provides the access while the cap provides the seal.

    Who's gonna provide the beer? This info don't come cheap, ya know!
    Is this a Fabreze moment? C.Y.D. I'm voting white elephant. 2.
    My competition are my best salespeople!

  5. #5
    Join Date
    Apr 2008
    Location
    On the roof
    Posts
    136
    Apple juice
    If you didn't do it right the first time it probably makes sense that your here asking the right way to do it now

  6. #6
    Join Date
    Nov 2004
    Location
    North Carolina
    Posts
    443
    Both. Now, guess which one is the primary and which one is the backup.

  7. #7
    Join Date
    Apr 2008
    Location
    Alberta Canada
    Posts
    2,246

    It is only rubber

    The cap is what protects the loss during cool days.
    Do it right the first time.

  8. #8
    Join Date
    Mar 2008
    Location
    North Queensland, Australia
    Posts
    1,050
    Generally the valve seals pretty well. but they can get crap under the seat. I've had ice build up in the valve and push the core down. I've seen the valves on discharge lines seats fail due to over heating. On the same valve I've seen the brass caps rubber seal fail for the same reason (heat).
    When we get refits in the local supermarkets the commissioning bloke goes round and replaces all the quickseal brass caps with flare nuts and copper bonnets. He says it's cheaper than replacing a charge in a rack
    Mistakes are a part of being human. Appreciate your mistakes for what they are: precious life lessons that can only be learned the hard way. Unless it's a fatal mistake, which, at least, others can learn from. Al Franken, "Oh, the Things I Know", 2002

  9. #9
    Join Date
    Feb 2001
    Location
    Arizona
    Posts
    5,460
    Quote Originally Posted by Joe Cool View Post
    The valve core only seals long enough so you can remove you gauges and put the cap on which actually seals it. Not saying it is going to leak, but it won't leak for sure if the cap is tightened down on it.
    Ditto!

    You guys don't even want to get me started on this sh*t!

    Several years ago I watched a tech at Charlie leak check a system for leaks.

    He walked up to the unit. Removed the king valve cap (without a wrench because it was just screwed on by hand at install) and stuck his leak detector into it. It detected a small leak.
    So what did he do? Order and replace the king valve like so many others who worked there!!!

    I'm like, "DUDE! That valve has a o-ring that is ONLY meant to seal while you open or close the valve. it is NOT a perfect seal. the CAP is. But you must CRUSH the cap on another 1/6th of a turn beyond hand tight AS the instructions said (if they readed them)!
    Same thing goes with the schrader valves. They will replace the core, because it leaked. But there either was no cap, or a plastic cap that had the o-ring missing, or a Trane cap that again was left HAND TIGHT!

    I just saw one the other day on a Trane Voyager that someone FILLED THE CAPS WITH LEAK LOCK and screwed them on!
    The core is full of leak lock and I didn't dare put my hose onto it!
    I instead unscrewed the pressure switch and used it's schrader.

    I couldn't believe that. I took video but haven't uploaded it yet.
    True Heavy Metal Geek

  10. #10
    Join Date
    Aug 2001
    Location
    forney texas
    Posts
    17,827
    neither one stops the leak. a schrader port is a hole in an otherwise sealed system. this hole leaks it must be stopped with a schrader valve and a cap with O-ring.

  11. #11
    Join Date
    Feb 2001
    Location
    Arizona
    Posts
    5,460
    Quote Originally Posted by acmanko View Post
    neither one stops the leak. a schrader port is a hole in an otherwise sealed system. this hole leaks it must be stopped with a schrader valve and a cap with O-ring.
    I think we are talking about which one is the SEAL. The cap or the core.

    If I can't hear a core leaking, I'm not replacing the core because it's doing it's job. It just needs to hold the charge when I remove the cap to put my gauge on. The cap however MUST seal.

    Looking how a core is made, I always find it a miracle if a unit isn't low on charge when the cap is missing, loose, or has a bad seal.
    True Heavy Metal Geek

  12. #12
    Join Date
    Apr 2007
    Posts
    6,285
    The valve core.

    If the cap is put on to tight it warps the body where the valve goes.

    If the valve gives out the cap is still there with the oring to minimize loses.

    If valves blow they let it all out. I believe the thinking behind the cap is sto slow the leak down till someone identifies they have a problem before ref. is completely out.

    Lots of system you walk up to have no caps on them and I don;t find many of just the valves leaks.

    I have found valves that were shot or leaked slightly and with the cap on and you pull it off you hear "tiss" for a sec.

    to minimize loss there is a primary....the valve...and the secondary back up the valve....to keep out debris.

    If they have plastic caps they are really only to keep debris out while at least the brass ones can serve as a temp means to keep excess ref. from escaping in case of valve core failure.

  13. #13
    Join Date
    Jan 2006
    Posts
    1,120
    All in all i check for a leak after I tighten the cap,cause after that who gives a rats ass if the valve core leaks or not.
    There are three signs of old age.
    The first is your loss of memory,
    the other two I forget.


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