Natural gas

[OldJalopy]

Just a question; will an engine designed for NG run the same on Propane? ron

[Kevin O. Pulver]

I do boiler work, and you can run them on propane or natural gas, but since the fuels are different, you need a different sized orifice to meter the fuel into the burner. Automobiles are made to run on both fuels too.
How much differently the engine will run, I confess I do not know.

[OldJalopy]

Thanks, but since the ges engine has spark for ignition I don't think it would be the same as a gas burner. I guess I could experiment but don't want to end up in the newspaper............................

[Chris Epping]

They will run on either. On more modern industrial engines the carb is the same, but it takes a different regulator as they run at different pressures. On these old engines, to run safely on LP, you'll need a demand regulator if you're trying to run a hit and miss engine. Otherwise your fuel is flowing in even when the engine is coasting. On a throttler, you can run a standard LP regulator, you'll make your flow adjustment with a fuel valve on the side of the carb. And hook up to the vapor side of you tank (some tanks have liquid and vapor oulets - if it only has one it's probably vapor).

Chris

[Jerry Sweet]

Yes,Natural gas and LPG engines normaly run a little higher compression ratio (like 10:1).The carburetors are designed for ether one.with LPG,if you pull vapor off the tank,you can normaly run up to about 10 H.P. without the tank icing.If you pull liquid off the tank,you can go on up in H.P.,but you will have to use a liquid regulater (LPG regulater)ahead of the carburetor.The LPG regulator has a built in heat exchanger that raises the temp.and turns the liquid to gas before it drops the pressure.

[Kevin O. Pulver]

Old Jalopy,
Gas engines can use hot tube, ignitor, or spark plug. Boilers too, (and furnaces) can use hot surface ignition, or spark ignition. I don't think the source of ignition is the dangerous part, it's the fact that fuel in the gaseous state can be leaking without it being obvious like a liquid leak. That is why they actually add a "stink" to natural gas- so you can smell if it's leaking.
Inside a sealed structure this is much more dangerous of course. And the REALLY dangerous part about LP (propane) is that it's heavier than air. Therefore, it will "pool up" up on the floor until it reaches the level of the ignition source, and BANG! Threaded and flare fittings should be leak tested with soapy water or a commercial sudsing liquid.

[OldJalopy]

Excellent; very good ideas and cautions. Seems like propane is more volatile and the carburetor jetting would work differently, I think the inlet lines are larger on a NG engine than one operated on propane and the inlet pressures different.

[Bob Willman]

They both should work but there are differences. The BTU/cubic ft of methane is about 1011 and propane is 2521. The explosive limits of fuel to air mixture for methane is from 5% to 15% and propane is from 2% to 9%. Methane is much less critical on explosive mixtures. I have noticed on my 2 cycle 25hp Superior that the governor has much more effect on natural gas than on propane. I suspect that enough propane leaks past the governor throttle valve so that the gas cock has more impact than the governor valve. At a heavier load there may not be as much difference.

Bob
WB8NQW