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Running a Liquid Propane Generator On Vapor?


...Can this be done???... ...I have an Onan Emarald 6300 lpg gen... The trailer I am installing...

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Old 11-09-2011, 09:16 AM
Willie B Willie B is offline
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Default Running a Liquid Propane Generator On Vapor?

...Can this be done???... ...I have an Onan Emarald 6300 lpg gen... The trailer I am installing it in is vapor... ...Can I run it on vapor or do I have to turn a tank upside down or pull liquid from one of the tanks (copper tube to the bottom) or???...

...Direction on this appreciated... ...Thanks Bill...
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Old 11-09-2011, 09:26 AM
K D Redd K D Redd is offline
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Default Re: Running a Liquid Propane Generator On Vapor???

What makes you think it was set-up for liquid LP feed? Most small generators like this are set-up for vapor feed. Post picture of the equipment have. I did many years ago see a ONAN installation manual showing a liquid Feed set-up where they wrapped the fuel line twice around the exhaust pipe to heat the liquid LP so when it changed to vapor in the regulator it would not freeze up the regulator.

Kent
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Old 11-09-2011, 09:37 AM
Willie B Willie B is offline
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Default Re: Running a Liquid Propane Generator On Vapor???

...Thats exactly what I have a gen with a fuel line wrapped around the exhaust manifold...
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Old 11-09-2011, 09:55 AM
mrmegoo mrmegoo is offline
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Default Re: Running a Liquid Propane Generator On Vapor???

Most new LP tanks today are OPD type & are designed to prevent liquid overfilling. This might block off the valve if turned upside down. If you have space for another tank, I would suggest a forklift type that can be used vertical or horizontal & is liquid withdrawal. I have seen this on a lot of horse trailers.
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Old 11-09-2011, 10:02 AM
Jim Rankin Jim Rankin is offline
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Default Re: Running a Liquid Propane Generator On Vapor???

you can try it, it may work just fine if you have enough tank surface area for the temperature you are running in.

or, it may not have enough pressure to push enough vapor through the regolator and mixer orifices to supply it under load. A partial solution to this is to tap in before the regulator and feed the generator vapor at tank pressure, so it (initially at least) has the same pressure coming to it as it was designed for.
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Old 11-09-2011, 04:28 PM
jht1057 jht1057 is offline
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Default Re: Running a Liquid Propane Generator On Vapor???

Your generator is still running on vapor, seems to me you just need to use a different regulator. The purpose behind the liquid feed was to avoid freezing the fuel tank and dropping pressure, by vaporizing the liquid at the regulator, instead of in the tank.

Jim
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Old 11-09-2011, 06:51 PM
bobbyz72 bobbyz72 is offline
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Default Re: Running a Liquid Propane Generator On Vapor???

You might feed it liquid propane, but it runs on vapor.
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Old 11-21-2011, 08:50 PM
Willie B Willie B is offline
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Default Re: Running a Liquid Propane Generator On Vapor???

Quote:
Originally Posted by Jim Rankin View Post
you can try it, it may work just fine if you have enough tank surface area for the temperature you are running in.

or, it may not have enough pressure to push enough vapor through the regolator and mixer orifices to supply it under load. A partial solution to this is to tap in before the regulator and feed the generator vapor at tank pressure, so it (initially at least) has the same pressure coming to it as it was designed for.
...I am getting close to plumbing for the propane... ...Have any of you tried to tap in before the regulator at the tanks???...
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Old 11-22-2011, 08:31 AM
Jim Rankin Jim Rankin is offline
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Default Re: Running a Liquid Propane Generator On Vapor???

Have you tried it with low pressure vapor yet? That would be simplest of all.

Not knowing what kind of cylinders etc you have, but it should be possible to get a T fitting that will allow you to tap in before the regulator if the generator won't pull a load on low pressure vapor. Like I mentioned, this is going to be a partial solution at best. As the generator pulls vapor from the tank (at any pressure) the tank will get colder until the pressure inside may get lower than the 11" WC your low pressure regulator puts out. It takes heat (from outside air, from a heating band you can buy, from engine heat etc) to keep this from happening.
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Old 11-22-2011, 09:07 AM
K D Redd K D Redd is offline
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Default Re: Running a Liquid Propane Generator On Vapor?

The OPD valve on 20 LB LP tanks WILL NOT allow you to feed ANYTHING with liquid by turning the tank upside down. This was done to prevent people from filling the 11 OZ throwaway LP tanks from a 20 LB tank.

Kent
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Old 11-22-2011, 09:17 AM
Phil P Phil P is offline
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Default Re: Running a Liquid Propane Generator On Vapor?

Hi

I have a forklift that uses liquid. The regulator has cooling water running thru it to keep the regulator from freezing. I have operated it on vapor without any problem. The regulator doesn’t seem to notice the difference. I also have installed a new regulator a few months ago and it still runs on vapor which I do while my wife takes the Liquid tank to get it filled.

Phil P
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Old 11-22-2011, 10:47 AM
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Default Re: Running a Liquid Propane Generator On Vapor?

The way it works. You will feed liquid from the tank into the vaporiser. This is the part wrapped around the exhaust system. It turns the liquid to vapor then feed the vapor to the system.
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Old 12-09-2011, 04:46 PM
Willie B Willie B is offline
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Default Re: Running a Liquid Propane Generator On Vapor?

...Thanks guys...

...I have my choice of 1/2 or 3/8 copper to run from the tanks to the gen...

...I bought 1/2 and then realized the rest of the trailer is plumed with 3/8... ...Which size should I use???... ...Would the 1/2 allow slightly more propane to be available to the gen...
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Old 12-09-2011, 06:59 PM
MadMachinist MadMachinist is offline
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Exclamation Re: Running a Liquid Propane Generator On Vapor?

Willie,

Not sure how you plan to plumb this thing up but in a previous post you asked about tapping in ahead of the regulator. I am not an expert on propane but I would never connect directly to the tank with anything that isn't designed to be.

At 90 degrees F, the vapor pressure of propane is going to be about 150 p.s.i.

The high pressure regulator at the tank reduces the pressure to a level that should still supply your set through 3/8 tube. My entire house is fed through a 1/2 inch tube about 80 feet long and all my appliances and furnace run on propane.

On the side of the house is a low pressure regulator that drops it to 11" water before it enters the home in the big black pipe.

If your set is setup for liquid draw, I would invest in a separate liquid system to feed it. Otherwise the small tanks will freeze up before they are empty on heavy demand.

Just my opinion
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Old 12-09-2011, 07:26 PM
K D Redd K D Redd is offline
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Default Re: Running a Liquid Propane Generator On Vapor?

When a engine is set-up for Motor Fuel LP with liquid feed, IT IS at tank pressure. It is hard to keep LP liquid at a pressure of 11 inch water column.
What size tank are you planning on using to fuel your generator? What ambient temperature will you likely see when you are using your generator? You should be able to feed the demand regulator you have with tank pressure But you will need to use a bigger line than what was used with the liquid feed because the small line will not flow as many BTUs per hour carrying vapor as it did liquid.

Kent
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Old 12-09-2011, 07:35 PM
Willie B Willie B is offline
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Default Re: Running a Liquid Propane Generator On Vapor?

...Thanks guys...

...I have my choice of 1/2 or 3/8 copper to run from the tanks to the gen...

...I bought 1/2 and then realized the rest of the trailer is plumed with 3/8... ...Which size should I use???... ...Would the 1/2 allow slightly more propane to be available to the gen...
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Old 12-09-2011, 07:43 PM
MadMachinist MadMachinist is offline
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Default Re: Running a Liquid Propane Generator On Vapor?

1/2 is bigger so 1/2 will allow more flow however; it will not make a difference if you freeze your tank.

Are you making a liquid or vapor connection?
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Old 12-10-2011, 12:28 AM
Willie B Willie B is offline
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Default Re: Running a Liquid Propane Generator On Vapor?

...Thanks...

...I should have added that there is a 3ft rubberish line that so far is designated to run from the vapor tanks to the copper line... ...This line came out of The Beaver motor home that the generator came from... ...The rubber line was used in a liquid feed system and has a pressure relief valve built into it... ...I do not know what the release point is on this valve,...and do not know if it is suitable for use witha a vapor system... ...is anyone familiar with this type relief valve???...
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Old 12-10-2011, 10:46 AM
K D Redd K D Redd is offline
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Default Re: Running a Liquid Propane Generator On Vapor?

The pressure relief valve were to protect your piping from bursting when valves were closed at each end of a liquid line. I set my old Dodge 400 up with these when I piped the LP Motor Fuel System on it. When I shut the system down, there is a closed Fuel lock at the Vaporizing Demand Regulator and the closed valves on the tank. If there is Liquid LP in the lines and the lines are exposed to summer temp and maybe direct sun light the pressure can go WAY up. I think, but do not know, these relief valves are set at the same pressure as any LP tank relief valve. That pressure is 312 PSI.

Kent
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Old 12-11-2011, 11:28 AM
Willie B Willie B is offline
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Default Re: Running a Liquid Propane Generator On Vapor?

...I am makind a vapor connection...

Quote:
Originally Posted by K D Redd View Post
When a engine is set-up for Motor Fuel LP with liquid feed, IT IS at tank pressure. It is hard to keep LP liquid at a pressure of 11 inch water column.
What size tank are you planning on using to fuel your generator? What ambient temperature will you likely see when you are using your generator? You should be able to feed the demand regulator you have with tank pressure But you will need to use a bigger line than what was used with the liquid feed because the small line will not flow as many BTUs per hour carrying vapor as it did liquid.

Kent
...The trailer has 2...7 to10 gallon (not sure which) old style valve tanks... ...The adapters I have seen so far,...that will tie in before the regulator at the tanks,...will tie me in to only one of the tanks... ...I have 2...30 gallon tanks that could be used if there is a need to run the gen more than just occasionly...

...The ambient temp where the trailer will be will be is 30*F in the winter to 118* in the summer...

...Don't worry guys,...I will not fire the gen until I am thouroughly confidant that it is plumed right and has been leak tested...

Thanks
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