Using LPG with CNG?

[Sharkbait]

I am trying to get a bit more range. Anyone heard of having a spare LPG BBQ tank with adaptors to fit and fill the CNG tank?

[TheBundo]

Re: Using LPG with CNG?

You wouldn't get much extra range, since the GX is essentially out of gas when it's down to 100 psi

[Curtis]

Re: Using LPG with CNG?

That would certainly result in an explosion of newsworthy proportions. LPG tanks are not rated anywhere near the pressures for cng. There are companies that will install auxilliary cng tanks. It runs about $2500 on average. You'll find some of them listed in the conversion forum. The big expense is the tank and would simply result in the loss of the remaining trunk space. Do a search for auxilliary tank with the "search" feature near the top of the page and you'll find the subject has been fairly well covered.

[freedml]

Re: Using LPG with CNG?

I've thought about this, too. The vapor pressure of LPG is about 32 psi but I don't think that's enough to open the filler check valve or get past the low pressure regulator under the hood. Curtis, there wouldn't be a pressure danger when connecting to the filler neck since only pressure from outside the car higher than the tank pressure can open the check valve. The tiny amount of LPG left in the system would go back to liquid when filled with CNG but I think that amount is so small as not to matter.

[ajgiorgi]

Re: Using LPG with CNG?

This sounds like an experiment that you would do with a pinto. LOL!

[Curtis]

Re: Using LPG with CNG?

I think he's talking about putting 3600 psi in the propane bottle (boom) and using it as a spare tank. Forget using the propane in the system for a number of reasons, including those Mike gave.

[philbert]

Re: Using LPG with CNG?

Oops, in that case, maybe I shouldnt have done it. I wondered about the same thing for my contour, so I made some adapters and filled up a barbecue tank. I guess I should take it out of the trunk and dispose of it? Is it really that dangerous?

[cngaz]

Re: Using LPG with CNG?

I'm just curious where you are filling it in Flagstaff?

[philbert]

Re: Using LPG with CNG?

I have an older fuelmaster and do it myself.

[Techie]

Re: Using LPG with CNG?

There is a way to do it safely, but it is pricey. You would have to install an add-on propane fuel system. It could either be a vacuum operated propane fumigation (not the best but works) or an add on propane fuel injection system. Grill tank only holds about 3 gals of propane, your GX will probably get about 15-18 MPG on propane. That will give you about 45 miles of driving or so.

Adding propane to the CNG fuel system will not work. The air fuel mixtures are way too different and CNG works at different pressures. Full tank gives you 3600 PSI. At about 200 psi, CNG system will alert you of low fuel. Grill tank usually has 150 psi in it on a warm day. Less on a cooler day. Propane fuel system flows liquid to the regulator, CNG flows gas. You got too many things here that are not compatible.

[Techie]

Re: Using LPG with CNG?

I think he's talking about putting 3600 psi in the propane bottle (boom) and using it as a spare tank. Forget using the propane in the system for a number of reasons, including those Mike gave.

He would have a very difficult time connecting a propane tank into the CNG system. The stainless steel lines on CNG system are very think, use unique fittings and do not cut easily. How is he going to connect a rubber hose from grill tank into that?

My guess is that he is talking about an add-on propane system, just in case he runs out of CNG.

[rkcarguy]

Re: Using LPG with CNG?

On the GX this won't work because of it's specialized CNG injectors. A mixer type system will run off either by simply changing the tank and regulator. Obviously you can't fill a LPG tank with CNG or it blows up like that idiots' did in India or somewhere.

[CNG MOTORS]

Re: Using LPG with CNG?

DO NOT FILL CNG INTO ANY LPG TANK....EVER!

[ajgiorgi]

Re: Using LPG with CNG?

DO NOT FILL CNG INTO ANY LPG TANK....EVER!

I think that sums it up!