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SHEMA trap ratings

The Steam Whisperer (Formerly Boilerpro)
The Steam Whisperer (Formerly Boilerpro) Member Posts: 834
in Strictly Steam
I am trying to compare trap capacities and some are rated as gross and others SHEMA.  What is the conversion formula for the SHEMA rating.



Thanks

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Comments

  • MikeyB
    MikeyB Member Posts: 696
    SHEMA

    Dave, I reached out to my trap Rep and he asked his guy at TLV and he mentioned that the SHEMA is a very old rating system for trap capacities that is no longer used, there is a conversion but if you could tell me your application/product that might help him find the info faster
  • The Steam Whisperer (Formerly Boilerpro)
    The Steam Whisperer (Formerly Boilerpro) Member Posts: 834
    Different makes etc.

    I am comparing capacities of different makes and models.  Illinois, Sarco, Tunstall, Barnes and Jones for replacements  Some of them are rated at SHEMA, others gross.  It appears that most companies are still using both SHEMA ratings and gross ratings in their charts.

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  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,600
    I think this is one of those areas where we can say

    it depends: http://bit.ly/15ZYnEg
    Retired and loving it.
  • The Steam Whisperer (Formerly Boilerpro)
    The Steam Whisperer (Formerly Boilerpro) Member Posts: 834
    Very interesting

    So the SHEMA capacity has nothing to do with the trap capacity but with the capacity of pipe it is connected too so it can still vent air.  So it best  to size of gross capacities when air is an issue.   I am looking at a trap that appears to be too small for the start up load.  The main it drains bangs on start up , then quiets down. A larger gross capacity would be good to handle the slug and then the air can begin venting again.

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  • DanHolohan
    DanHolohan Member, Moderator, Administrator Posts: 16,600
    That's the way I'm reading it, Dave.

    Love to hear the rest of the story. Thanks. 
    Retired and loving it.
  • MikeyB
    MikeyB Member Posts: 696
    SHEMA

    From my supplier:



    SHEMA ratings only apply to an F&T trap, Steam Manufactures Association (SHEMA)  providing for the continuous elimination of air when the trap is operating at its maximum rating. No safety factor need be applied. Actual capacities are significantly greater than SHEMA rating indicates.
  • The Steam Whisperer (Formerly Boilerpro)
    The Steam Whisperer (Formerly Boilerpro) Member Posts: 834
    And Thanks to you and the wall...

    .

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