# Propane, butane, CNG



## Yofy (Aug 15, 2007)

Does anybody happen to know how interchangeable these fuels are on galley stoves?

I would imagine that CNG is not interchangeable, but what about propane and butane? Do you need to change any parts on your stove/system if you change over the gas?


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## sailaway21 (Sep 4, 2006)

There are two ways of regulating gas pressures for different gases. One is via an orifice, as in a burner orifice. The other is via a regulating valve which may also require a different orifice, or may not. As suggested, you should contact the manufacturer of your unit. Generally speaking, it is not a difficult conversion to perform if the unit is designed to be used with different gases.


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## Faster (Sep 13, 2005)

Most gas appliance service outfits should be able to help you out.

Going from propane to CNG or vice versa is requires an orifice size change on most stoves. The connection fittings will likely also be somewhat different. A professional can get the information and parts you need for that.


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## Valiente (Jun 16, 2006)

While butane and I believe CNG is available widely in Europe, I believe CNG is very hard to find easily in North America. I can recall only a few service stations in Toronto that sell it, mainly because some delivery vans use it as a fuel. This is a shame, because CNG is arguably a superior fuel for boats, as it is lighter than air, and thus avoids the primary issue that propane has of leaking into the bilges and forming a "fog bank" of potential explosiveness.


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## sailingdog (Mar 19, 2006)

CNG isn't really all that available anywhere AFAIK. The problem is a chicken-and-the-egg situation...where companies don't want to install CNG sales terminals, since there is not much demand for it... and people don't buy CNG equipment, since the fuel is rather difficult to get. 

As for gas stoves... CNG works a very diiferent pressure and volumes than do butane and propane, which will generally work with the same burner and hoses. CNG is not compatible with copper pipes IIRC, which are often used on boats with propane/butane setups. 

CNG is not as good a fuel, since it is much lower in heat generated than propane or butane, but is a bit safer since Methane, the primary component of CNG, is lighter than air and will not tend to collect in the bilge or inside the boat to any major degree. Propane and butane both can collect in the boat's bilge and lead to a nasty explosion. I highly recommend any boat with a propane heating appliance, whether it is a stove or heater, have a propane fume detector, ignition safe bilge blower and a CO detector.

BTW, LPG, isn't always propane, but can often be a mix of propane and butane. Propane is a better fuel in the winter time or in colder conditions, since it remains gaseous down to about -40˚C, versus about 0˚C for propane. CNG is better in really cold weather, staying gaseous until about -150˚C.


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## sailaway21 (Sep 4, 2006)

Propane boils at about -27 degrees, IIRC.


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## sailingdog (Mar 19, 2006)

sailaway21 said:


> Propane boils at about -27 degrees, IIRC.


Survey says XXXXXXXXXXXX...Wrong again as usual... BTW, -40˚C = -40˚F...so it doesn't really matter what temperature scale you're using. 

Try looking *here*:



> Liquid phase
> Liquid density (1.013 bar at boiling point) : 582 kg/m3
> Liquid/gas equivalent (1.013 bar and 15 °C (59 °F)) : 311 vol/vol
> *Boiling point (1.013 bar) : -42.1 °C*
> ...


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## Yofy (Aug 15, 2007)

Thanks for all the replies. sailingdog, that was most helpful.

We have a force 10 propane stove that was installed in Canada and over here we've been using what we thought was propane, but just may be butane or even LPG with a combination of both with no problems. In fact I didn't even think of the issue until yesterday when...

a cruiser who sailed in here not so long ago came to me with the question. It seems that he originally installed CNG and a compatible galley stove when he first refitted in Michigan in the US. Since then he's been crusing for many years, slowly making his way across the pond, through Scandinavia and down through the Med. He's just come in here to refit a little before heading on down the Red Sea to India. (Quite a guy  ) He says that for each area that he's cruised he's had to change cooking fuels and he was wondering if he could get butane over here. 

That led to look at his galley stove, tank and fittings and then I got to wondering about compatibility...


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## copacabana (Oct 1, 2007)

"CNG isn't really all that available anywhere AFAIK. The problem is a chicken-and-the-egg situation...where companies don't want to install CNG sales terminals, since there is not much demand for it... and people don't buy CNG equipment, since the fuel is rather difficult to get." 

As a matter of fact, it's quite available in some countries. Both Argentina and Brazil have CNG at the pump in gas stations. I have two cars that run on CNG and the savings are amazing, not to mention they pollute less buring CNG. I can do 350km on one tank (costing about 8 dollars). That said, I think all the cooking gas here is LPG, but I'm not 100% sure. It just got me to thinking, the high pressure (200 BAR) CNG tanks for cars would make excellent stove tanks- you could store years worth of fuel in one!


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## Diva27 (Nov 2, 2007)

A few years ago on a previous boat I stumbled into a surefire (okay, bad analogy) way to get free propane all summer. I had a propane BBQ on the rail and didn't want to lug around a large propane cylinder. So I bought one of the small ones, and was pleased to discover that every time I took it to the local filling station, they couldn't figure out what to charge me and just kept filling it for free...over and over again.


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## sailingdog (Mar 19, 2006)

Copacabana-

Saying that CNG is available at the pump at gas stations doesn't mean that it is necessarily available at marina fuel docks, or anywhere close to the water. Also, Brazil and Argentina are just two countries, out of hundreds... getting fuel that is readily available in most cruising areas is important, unless you don't sail outside of Brasil and Argentina. 

The US has a fair number of CNG fueling stations, but they're difficult to find and I posted a website that has an alternative fuel station locator on it in a post earlier this year. However, the issue is finding fuel that is easily accessible, and right now CNG doesn't qualify as that in 99% of the world.

LPG is often a mixture of propane and butane, as I said earlier, and most stoves that are designed for propane or butane can burn a mixture or the other with little trouble. LPG, propane and butane have a much higher heat content than does Methane, the primary component of CNG. Also, since LPG, Propane and butane are stored in liquid form, you can store more if it in the same space...making it far more efficient in terms of use on a boat. CNG is not stored in liquid form...but is Compressed Natural Gas.


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## sailaway21 (Sep 4, 2006)

Dog,
You're making a rather fallacious point about compressability if you think about it. Let's acknowledge that you can cram a bit more propane into a given size container than you can natural gas. But the point is compression, ie...how close we can jam those molecules together under pressure. The fact that propane will liquify only means that the molecules are just a tiny bit closer than they were before as a gas. It also happens to mean that one should be more careful of heat generation when refilling such tanks and that one may experience frost up of fitting when running a tank wide open-neither serious concerns. CNG has tremendous advantages, availability not being one of them, and if sailor's were to decide to get up on their high horse about something, there'd be no better platform than demanding more sources for CNG. Let's not get so Irwin Corey obsessed with the science that we ignore the fact that CNG users have significantly safer bilges and that the lack of CNG stations is primarily a US issue in the main. You know, if it were readily available for refill, you'd be on here touting it's use over anything else-just for the energy and safety! (g)


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## sailingdog (Mar 19, 2006)

I'm not saying that CNG isn't a safer fuel for stoves. I fully agree that it is... but what good is a safer fuel if it isn't readily available. Given that CNG has much lower heating value, you need to either have larger tanks for the same amount of cooking, or refill the same size tank more often. Given the lack of availability, it really isn't a good option. It isn't as good an energy source IMHO, but it is safer in some respects, since it won't be as likely to gather in the bilge and has a higher low-end concentration limit for flammability—5% vs. 2.2% for Propane and 1.5% for Butane, as well as a higher ignition temperature.


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## copacabana (Oct 1, 2007)

Sailing dog, I wasn't suggesting that CNG is available wordwide, I was simply pointing out that in some countries (and I forgot to mention Bolivia!), it is very available and cheap. Also, you can use 200 bar tanks (like scuba tanks) and pack a lot of gas in a tank. In my car I have 2 tanks a little larger than a scuba tank each that hold 15 cubic metres. That's a lot of gas. One could probably go years cooking on board before having to fill up again.


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