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Balancing steam vent chart question

I am trying to find ounce per cfm for a legend t-60 valve (and others in the future, that are not in THE vent chart). Is there an equation that uses orifice size? I figure I can measure orifice with a drill bit, as manufacturer cannot provide any sizing or cross reference info. Thanks


  • SteamingatMohawk
    SteamingatMohawk Member Posts: 740
    If you can measure the orifice diameter, you can take a wild guess at flow capability by comparing it to the orifices in Maid O Mist radiator vents in the below table reference,


    then go to the vent chart for MOMs and see what you get for an answer. You may have to estimate between sizes. Just be aware that this is truly a wild guess, because any differences in the construction of the two radiator vents that could affect flow rate are not known.

    It's a good thing to do on a rainy day in winter.

    I also looked at a 1982 version of Crane Technical Paper 410, my bible when I was working, and it doesn't even go below 1 psi.

    If you search on "compressible flow through orifice" you can find several resources, but my guess is that they may not be applicable at such a low pressure and pressure drop.

    Good luck.

  • SteamingatMohawk
    SteamingatMohawk Member Posts: 740
    I did the easy part. Here's a chart of the Maid O Mist orifice numbers (4, 5, 6, C, D), orifice sizes and capacities in CFM.

    MOM.pdf 63.9K
  • chuckadoo
    chuckadoo Member Posts: 30
    That is a very useful reference! Thank you!
  • SteamingatMohawk
    SteamingatMohawk Member Posts: 740
    My pleasure, practice making charts helps my brain...