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How to attach cold trap to base plate?

  1. Apr 22, 2013 #1
    Hi,
    I am trying to think of a way to attach my water baffle/cold trap to the bottom of my base plate. The baffle is attached to a diffusion pump, meaning that I need a good seal between the plate and the baffle. I was thinking about drilling holes in the baffle and half way through the base plate, then tapping the holes and putting an o-ring on the baffle, inside of the screws to get a perfect seal. I am afraid I may not have enough room for this though, because the baffle is a toroid shape, so I might not be able to fit a screw through the hole from the bottom of the base plate. Is there an easier way to do this without screws??

    Thanks in advanced for the help
     
  2. jcsd
  3. Apr 22, 2013 #2

    Danger

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    May I ask, as politely as possible, what the hell you're talking about?
    You seem to be assuming that everyone already knows about your project and can just instantly envision the set-up. Wrong.
    Is this for an aquarium? A heart-lung machine? A fuel filter? (I know that your mention of water probably precludes the latter two, but not necessarily if purification is the objective.)
    How big is it?
    What materials?
    Can you at least post a sketch or photo of what you're doing?
     
  4. Apr 22, 2013 #3
    Haha sorry, I tried to upload an image, but it wasn't working and I was pressed for time when I posted this.

    Let me try to make it more clear. I am setting up a high-vacuum system for an SEM. I have a glass bell jar sitting atop a 12x12 inch aluminum base plate that is 1 inch thick. There is a 2 inch diameter hole in the plate that is for the diffusion pump. Before the diffusion pump there is a water baffle/LN2 cold trap.

    My question is simple and to be honest, doesn't really require a knowledge of my exact setup. I am asking how a diffusion pump or water baffle is typically attached to a base plate in a high-vac system. With the use of tapped screws and an o-ring?

    Thanks
     
  5. Apr 22, 2013 #4

    nsaspook

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    We have no idea of the type of flanges (ISO clamp or bolt, CF, KF or several other types) so it's impossible to say how to mount it without detailed information.

    http://www.mksinst.com/product/category.aspx?CategoryID=135
     
  6. Apr 23, 2013 #5

    Danger

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    Understood. No hard feelings.
    I'll leave this up to Nsaspook, though. He clearly knows more about this than I do.
     
  7. Apr 23, 2013 #6
    http://www.bmius.com/images/Product/medium/29449.jpg [Broken]

    Here is the baffle.
     
    Last edited by a moderator: May 6, 2017
  8. Apr 23, 2013 #7

    nsaspook

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    Last edited: Apr 23, 2013
  9. Apr 23, 2013 #8

    Danger

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    I see why they call it that; it's certainly baffling to me. :biggrin:
     
  10. Apr 23, 2013 #9
    I am concerned that I will not be able to get the screws to fit under the flange. In the picture, it seems as if the baffle is in the way of the flange bolt holes. Does this mean I would need to get some sort of extension piece in between the baffle and the base plate?

    Thanks again for your help
     
    Last edited by a moderator: May 6, 2017
  11. Apr 23, 2013 #10

    nsaspook

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    That's why thread studs are normally used for a test jig like yours. There should be plenty of space for a washer and nut to fit in between if the stud is the correct length. The correct way would be to have the mating (smooth) flange welded to the chamber plate with plenty of space to use the correct hardware.

    http://patentimages.storage.googleapis.com/EP0371579B1/imgf0002.png
     
  12. Apr 25, 2013 #11
    So if I were to do it the correct way, and the baffle diameter is 3.375", while my diff. pump is still 2", what type of connector would be appropriate to piece together my baffle to my diff pump?

    EDIT: the diff pump is a flat 90 deg. smooth flange
     
  13. Apr 26, 2013 #12

    Danger

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    Hi again.
    While I don't want to hijack this, I do have to ask one question that's driving me nuts.
    Nsaspook, I've seen a pretty wide variety of locking mechanisms, but I can't for the life of me figure out what that single left-hand thread on the bottom of the stud in figure 5 is all about. How did it even get in there?
     
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