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Gas orifice design

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ChrisJ
ChrisJ Member Posts: 15,677
edited December 2017 in THE MAIN WALL
Hi all.

I would ask @Tim McElwain but I think he's got more important things to deal with at the moment.

Gas orifice drill sizes are readily available but what I can't find is the length of the orifice. As in fine I need a #31 drill size but how deep should it be at that dimension before going larger?


We made this where I work to convert an outdoor lpg hurricane burner to NG.
Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment

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  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,525
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    I would think you would drill it all the way through. Are you concerned with the orifice being long that the #31 will be too restrictive at that length??

    most orifice's are about the size of an 1/8 pipe plug so I guess if it's a long orifice drill it oversize and leave a 1/4" drilled at #31.

    Just guessing. Anyway to clock the meter after drilling to check it out?
  • ChrisJ
    ChrisJ Member Posts: 15,677
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    > @EBEBRATT-Ed said:
    > I would think you would drill it all the way through. Are you concerned with the orifice being long that the #31 will be too restrictive at that length??
    >
    > most orifice's are about the size of an 1/8 pipe plug so I guess if it's a long orifice drill it oversize and leave a 1/4" drilled at #31.
    >
    > Just guessing. Anyway to clock the meter after drilling to check it out?

    Yeah that's what I'm concerned about. I'm hoping there's engineering data out there for it.

    I'm hoping to fire it up this weekend to see how it works.
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Bob Harper
    Bob Harper Member Posts: 1,035
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    There are charts in NFPA 54' showing BTU flow rates for a given orifice at a given pressure for a given gas.
  • ChrisJ
    ChrisJ Member Posts: 15,677
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    Bob Harper said:

    There are charts in NFPA 54' showing BTU flow rates for a given orifice at a given pressure for a given gas.

    Yes.
    And none of them specify how long the orifice is, only it's diameter.

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • ChrisJ
    ChrisJ Member Posts: 15,677
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    @captainco Any thoughts on the length of an orifice? Is there a design spec for it?

    Like I said I need a #31 orifice diameter but how long? It's got to have an effect to an extent unless anything 1/2" to 1/16 is considered fine
    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • ratio
    ratio Member Posts: 3,626
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    It looks like as thin as possible yet able to withstand the forces applied: see http://www.springer.com/cda/content/document/cda_downloaddocument/9783319168791-c2.pdf?SGWID=0-0-45-1505283-p177306192

    See § 2.5.5 in particular.

    Until you end up with what's basically as piece of pipe, I doubt that it matters much for our application.

    ChrisJ

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