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Medical Vacuum Stainless Steel Installation

  • Wednesday, December 09, 2015 8:04 PM
    Message # 3691049
    Al Moon (Administrator)
    Based on this photo, is this installation acceptable for medical vacuum systems and would it pass verification?



    Last modified: Wednesday, December 09, 2015 8:08 PM | Anonymous
  • Friday, December 11, 2015 4:25 PM
    Reply # 3694521 on 3691049

    This looks like an acceptable transition from stainless steel to copper. 

     

     

    Certain editions did not allow branches to come from the bottom of the main.  This requirement has since been removed, but is still a good idea.

  • Friday, December 11, 2015 5:11 PM
    Reply # 3694562 on 3691049
    Al Moon (Administrator)

    Sorry, I needed to rotate the picture. But, my question is does NFPA 99 allow bolted connections ?   I understand that the service ball valves will always have a bolted connects for it to be three piece.

  • Monday, November 26, 2018 12:32 PM
    Reply # 6933274 on 3691049
    Steve Bradshaw (Administrator)

    The fitting must be permanent and the seal must have a melting temperature of at least 1000 deg F.  (I realize that 3 piece shutoffs are not permanent and don't meet the melting temperature)


    The code permits dissimilar metals to be brazed.  Welding is permitted but copper and stainless don't have the same dimensions to make this practical.

  • Tuesday, November 27, 2018 6:51 AM
    Reply # 6934605 on 3691049
    Cary Darden (Administrator)

    I'm not seeing anything that directly addresses this joint (two flanges bolted together with a gasket).  There is a list of prohibited joints which this doesn't seem to fit into:


    5.1.10.10 Prohibited Joints. The following joints shall be

    prohibited throughout medical gas and vacuum distribution

    pipeline systems:

    (1) Flared and compression-type connections, including

    connections to station outlets and inlets, alarm devices,

    and other components

    (2) Other straight-threaded connections, including unions

    (3) Pipe-crimping tools used to permanently stop the flow of

    medical gas and vacuum piping

    (4) Removable and nonremovable push-fit fittings that

    employ a quick assembly push fit connector


    Then there is a statement about special fittings:


    5.1.10.9 Special Fittings.

    5.1.10.9.1 Listed or approved metallic gas tube fittings that,

    when made up, provide a permanent joint having the mechanical,

    thermal, and sealing integrity of a brazed joint shall be

    permitted to be used.


    It doesn't really meet that because it isn't permanent.  


    Here is my question, since this is vacuum why didn't they just put a butterfly valve in between those two flanges and save the cost of the ball valve on the other end?



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