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Thread: Gas / Propane Generators

  1. #1
    Join Date
    Jan 2014
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    plymouth ma
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    6

    Gas / Propane Generators

    Good Morning,

    I have (2) NATURAL GAS Caterpillar generators (G3512) 555KW / 208volts

    These Generators will also run on propane, KW drops down to 380KW / 208volts

    My problem is they won't run on propane.

    (2) 1,000 gallon propane tanks in the ground, vaporizer has been replaced twicedue to being outside and weather conditions etc...

    When I switch from natural gas to propane, the (1) incoming 2" pipeline starts to frost up, the 2 engines start to rev up and down.

    The (1) 2" pipe comes into the building and branches off to feed thegenerators. Each of the engines has their own factory installed regulator.

    There is also regulator out at the vaporizer.

    Any direction, advice greatly appreciated.
    Thank You

  2. #2
    Join Date
    Oct 2007
    Location
    New Jersey
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    4,434
    Quote Originally Posted by fayc11 View Post
    Good Morning,

    I have (2) NATURAL GAS Caterpillar generators (G3512) 555KW / 208volts

    These Generators will also run on propane, KW drops down to 380KW / 208volts

    My problem is they won't run on propane.

    (2) 1,000 gallon propane tanks in the ground, vaporizer has been replaced twicedue to being outside and weather conditions etc...

    When I switch from natural gas to propane, the (1) incoming 2" pipeline starts to frost up, the 2 engines start to rev up and down.

    The (1) 2" pipe comes into the building and branches off to feed thegenerators. Each of the engines has their own factory installed regulator.

    There is also regulator out at the vaporizer.

    Any direction, advice greatly appreciated.
    Thank You
    IIRC, when you switch you have to change the orifice/regulator size for generators. This is the same for a variety of propane/NG appliances. I would guess you need a second set of regulators for the propane.

  3. #3
    Join Date
    Nov 2015
    Location
    Ellington, CT
    Posts
    24
    How far are the generators from the fuel source? How many bends? Hunting ( revving up and down)is normally indicative of fuel/air mixture being off. I have spent many years on installing and servicing generators. The 2" line feeding 2 generators doesn't seem adequate as evidenced by the line freezing. That tells me that the draw on that line is extremely high. What is the required water column v.s. the incoming water column? This will also predicate pipe size.

    Sent from my XT1254 using Tapatalk

  4. #4
    Join Date
    Oct 2007
    Location
    New Jersey
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    Leaving aside any regulator issues, if the lines are frosting up after the vaporizers, that means the vaporizers are too small. You need more of them or larger ones.

  5. #5
    Join Date
    Jan 2014
    Location
    plymouth ma
    Posts
    6
    Thank You

    I will get back to you with some answers

  6. #6
    Join Date
    Dec 2012
    Location
    Placerville, CA, USA
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    17,960
    Quote Originally Posted by gadfly56 View Post
    Leaving aside any regulator issues, if the lines are frosting up after the vaporizers, that means the vaporizers are too small. You need more of them or larger ones.
    And if they are frosting up before the vaporizers, you are not actually supplying liquid to the vaporizers.

    Sent from my XT1585 using Tapatalk

  7. #7
    Join Date
    Nov 2015
    Location
    Ellington, CT
    Posts
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    I forgot to ask......what is the conversion method to go from ng to lp? On most generators, the orifice needs to changed.

    Sent from my XT1254 using Tapatalk

  8. #8
    Join Date
    Dec 2012
    Location
    Placerville, CA, USA
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    Quote Originally Posted by bsmith8691 View Post
    I forgot to ask......what is the conversion method to go from ng to lp? On most generators, the orifice needs to changed.

    Sent from my XT1254 using Tapatalk
    Typically two things get changed:

    1. The orifice(s) in the generator carburetor,
    2. The input pressure regulator setting (may be part of generator or external to it.)

    In other words, the pressure at which LPG vapor is supplied to the engine will be different from the corresponding NG pressure.
    Last edited by GoldDigger; 05-12-17 at 10:02 PM.

  9. #9
    Join Date
    Dec 2007
    Location
    NE Nebraska
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    Quote Originally Posted by fayc11 View Post
    Good Morning,

    I have (2) NATURAL GAS Caterpillar generators (G3512) 555KW / 208volts

    These Generators will also run on propane, KW drops down to 380KW / 208volts

    My problem is they won't run on propane.

    (2) 1,000 gallon propane tanks in the ground, vaporizer has been replaced twicedue to being outside and weather conditions etc...

    When I switch from natural gas to propane, the (1) incoming 2" pipeline starts to frost up, the 2 engines start to rev up and down.

    The (1) 2" pipe comes into the building and branches off to feed thegenerators. Each of the engines has their own factory installed regulator.

    There is also regulator out at the vaporizer.

    Any direction, advice greatly appreciated.
    Thank You
    I agree you likely have orifice/regulator issues, possibly failure to change/adjust something when switching fuel type. Output rating is usually higher on same unit when supplied with LP than it is for NG, but you stated it was higher for NG.

  10. #10
    Join Date
    Jan 2014
    Location
    plymouth ma
    Posts
    6

    Name plate on Generator... NaturalGas 555kw, Liquid Propane 363kw,

    The High Pressure Natural Gas line feeds into one end of the generator engine,has its separate solenoids, it’s on separate regulators etc...

    The Liquid Propane Line feeds in on the other end of the generator engine andit has its own separate solenoids, it’s on separate regulators etc...

    Caterpillar has told me that it can switch over to propane if we were everrunning and we lost the natural gas line? I would know that because it’s neverrun on propane since the beginning.


    The propane line frosts up after the vaporizer


    I had a mechanical / plumbing engineer look at it, hesuggested electric vaporizer? Remove the regulators from the generator enginesand just have one regulator out at the vaporizer?
    I don’t think Caterpillar will go along with removingregulators from the engine.

    If I looked at this backwards…

    I got a Cat Generator, runs on propane, 363kw output with propane fuel
    What size pipe line needed to feed the engine fora 363kw output?
    What size Vaporizer is needed?
    The regulator out at the vaporizer is set for? Psi?
    The regulator at the engine is set for? Psi?
    Is a mechanical / plumbing engineer the best one to call?
    Is a Caterpillarengineer the best one to call, (I tried thatand got no where)


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