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Alcohol to Propane Stove Conversion Question.

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Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Initially Posted - 04/14/2003 : 13:05:02

Hey, I have a question for those of you who converted your old pressure alcohol stove to propane. What did you do about pressure regulation?

The Century "Trail Scout" 8,000 BTU propane camp stoves are intended to screw directly on to a disposable propane cylinder, which would be pressurized to over 100.PSI on a warm day, right?

The propane hook-up hoses available are intended for low pressure use at around 1/2PSI, right?

When I ran full tank pressure to the burners, they worked normally. When I installed a low pressure regulator, and ran around 1/2PSI to the stove burners, no flame came out. The most obvious reason I can see is the microscopic gas metering jet where the propane gets mixed with combustion air inside the burner.

Did y'all modify that gas jet?

Did you run full tank pressure to the stove?

Where did you install your propane tank (when in use)?

Am I missing something here?

-- Leon Sisson

Edited by - on

Douglas
Master Marine Consultant

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1595 Posts

Response Posted - 04/14/2003 : 13:45:01

Inside the valve that screws onto the cylender is a very small metering jet. It acts similar to a pressure regulator by only alowing the right amount of fuel to pass through. Think about you ordinary propane torch or lantern. They to do not have regulators just the on / off metering valve. You dont need to mod the jet, yes you can run just the can and valve. The stove will never see the full presure due to the metering valve inside the shut of valve. You can use a long 6' gas line and set the bottle in the cockpit.

Doug&Ruth
Triska (Alberg 29)
Tacoma Wa.

Edited by - on

OJ
Master Marine Consultant

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USA
4382 Posts

Response Posted - 04/14/2003 : 14:08:53

Leon,
When I hear "bottle" I think disposable which (to the best of my knowledge) does not require a pressure regulator. When I hear "tank" I think of refillable which does require a regulator.
I'm using a 5 lb tank on OJ. I installed a pressure regulator inside my stove to keep it out of the way.
Let me know if you need a source for the regulator.
Good luck.

Edited by - OJ on 04/14/2003 14:12:03

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Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 04/14/2003 : 14:44:54

Doug&Ruth,
<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>... valve that screws onto the [disposable] cylinder [has] a very small metering jet. It acts similar to a pressure regulator by only allowing the right amount of fuel to pass through. The stove will never see the full pressure due to the metering valve inside the shut of valve.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>I agree with your description of what's there, but not how it operates. The hole in the end of the probe that goes into the disposable propane cylinder to open the valve is much larger than required for all but the hungriest appliance. Even if that is the "regulator", with the stove temp control valves turned off, the pressure in the hose will instantly climb to whatever the pressure is in the tank, which can be quite high. I agree that the Century "Trail Scout" propane camp stove relies on metering orifaces to regulate fuel delivery to the burner. There's the one in the end of the tank valve probe, there's the needle valve used to adjust the cooking flame, and there's a very tiny jet right where the propane is first mixed with combustion air inside the burner. I think that last one is the safety, which prevents the stove flame from flaring up so much that the startled cook can't (or won't) put their hand on the tempurature knob to shut off the fuel flow.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>You can use a long 6' gas line and set the bottle in the cockpit.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>Mine is a semi-permanent installation, in which the tank has a mount (not in the cabin), a manual cutoff valve at the tank, and enough permanently installed hose to reach the stove. That comes out to about 15' of 3/8" hose. When I turn off the tank, the stove burners continue to run at full heat for over 10 minutes. That's a lot of pressurized gas in the hose, which is inside the cabin, and probably not intended for high pressure use.

OJ,<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>When I hear "bottle" I think disposable which I (to the best of my knowledge) does not require a pressure regulator. When I hear "tank" I think of refillable which does require a regulator.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>I'm sorry if I've been misleading about my choice of propane containers. Initially, I installed a disposable "torch" sized bottle. After seeing how few meals one of those would cook, I'm now considering an aluminum 5# tank like you have. Either way, the gas pressure coming out of the tank is the same. The difference seems to be that some appliances are designed to run off full tank pressure, and some are intended to be on the low side of a regulator. Additionally, it seems there are two types of active regulators (those with moving parts): some are adjustable around 35.PSI output, and some have a fixed output around 1/2PSI.

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>I'm using a 5 lb tank on OJ. I installed a pressure regulator inside my stove to keep it out of the way. Let me know if you need a source for the regulator.<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>This sounds like you're running your hose at tank pressure, is that correct? What's the output pressure of your regulator? Are you using the Century "Trail Scout" propane camp stove burners in a converted Optimus Princess stove housing, or some other type of propane stove?

Thanks for all the help!<img src=icon_smile.gif border=0 align=middle>

-- Leon Sisson

Edited by - on

OJ
Master Marine Consultant

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USA
4382 Posts

Response Posted - 04/14/2003 : 19:21:36

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
This sounds like you're running your hose at tank pressure, is that correct?
If you mean I don't have a regulator mounted on the tank - then yes that is correct (again, I didn't want to have a regulator sticking out from the tank begging to be broken off.) I do, however, have have a regulator inside the stove that the hose from the tank screws into. From the regulator I have a tee fitting to feed the two burners.
What's the output pressure of your regulator? Man Leon! you're my kind of do-it-my-selfer - I wish I knew the answers to these questions but the customer service person at BP Products couldn't even tell me if I needed a pressure regulator or not! Please share these specs once you have them.
Are you using the Century "Trail Scout" propane camp stove burners in a converted Optimus Princess stove housing, or some other type of propane stove? Same, same

BTW, if I had to do over again I think I'd order the 11 lb. tank - it's still pretty compact. 

<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

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Dave Bristle
Master Marine Consultant

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Djibouti
10005 Posts

Response Posted - 04/14/2003 : 20:31:51

My only propane experience is with gas grills, but every one of them has a regulator that screws into the tank. I agree that otherwise the pressure in the hose will be too high--regardless of the tank size. Liquid propane stays liquid a a specific pressure, which is substantial (and the reason for the containers being substantial).

I also recall that a C-250 I looked at had a factory-installed LP system with a safety shutoff and regulator system in the cockpit locker--I don't remember any more than that, and I may have even mischaracterized it.

Anyway, in my humble opinion, a regulator MUST go on the tank side of the hose. Otherwise, you're begging for a very dangerous surprise anywhere along the hose, and most likely at the opposite end.

Dave Bristle - 1985 C-25 #5032 SR-FK-Dinette-Honda "Passage" in SW CT

Edited by - on

RichardG
Admiral

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USA
990 Posts

Response Posted - 04/14/2003 : 21:03:05

Man -- you guys are making the original curtain burner sound better and better!

RichardG 81 C25 SR/FK "Sanity"

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OJ
Master Marine Consultant

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USA
4382 Posts

Response Posted - 04/15/2003 : 11:25:11

Hey, quiet in the peanut gallery. There's genius at work here. Not sure where, but it's in here somewhere.

Edited by - on

Douglas
Master Marine Consultant

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1595 Posts

Response Posted - 04/15/2003 : 12:43:15

Big tank = regulator

Small propane cylender (torch type) = no regulator

cant make it any easyer than that

Doug&Ruth
Triska (Alberg 29)
Tacoma Wa.

Edited by - on

OJ
Master Marine Consultant

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USA
4382 Posts

Response Posted - 05/07/2003 : 10:32:33

Leon,
How are you progressing with this project?

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Leon Sisson
Master Marine Consultant

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USA
1893 Posts

Response Posted - 05/07/2003 : 12:18:04

OJ,<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>Leon,how are you progressing with this project?<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>My propane installation passed insurance survey, and I've been cooking meals aboard. Last night it was kingfish and onions sauteed with curry, ginger, and soy sauce. On the other burner, I fixed spanish rice in a double boiler.<img src=icon_smile.gif border=0 align=middle> The cat dined on raw kingfish scraps.

As for the mechanical details -- what I ended up doing is this. I'm using the shorter wider 16oz. disposable propane containers. The one in use is installed in the shallow stbd. cockpit locker. That locker now has a 1/2" PVC drain from its lowest point into the cockpit footwell. Starting from the tank threads, there's the required throwaway-to-1/4"MNPT brass adapter. Next is a 3/8" gas-rated ball valve with appropriate brass threaded adapters. After the cut-off is a gas pressure regulator set to maybe 10.PSI. This regulator is adjustable, but came with no documentation, and I haven't put a pressure gauge on the output side to test its actual range.

From the regulator, gas-rated hose snakes through a hole high in the aft wall of the locker, down through the quarterberth bookshelf, into the skeg, forward around the front of the huge port cockpit locker, past the galley thru-hull, up through a hole in the outboard wall of the stove shelf. There's a half-loop of hose under the stove to allow for gimbal motion.

Under the stove, the conversion is more or less like the photos that have been posted. At the burners, I changed the final gas safety metering jet to accommodate the lower line pressure from the regulator. The cheap and elegant way would be to precisely ream out the Century "Trail Scout" jet, if only one knew for certain what size to make the hole (and if one were capable of making precise holes that small). Not being that clever, I bought another Century camping stove, the propane equivalent of the venerable Coleman two burner white gas stove. This came with a lame looking pressure regulator marked "17PSI". I extracted the final gas safety metering jets from that stove, and substituted them into the Century "Trail Scout" burners. The resulting flame is a bit "soft" compared to what one expects to see. There are no sharply defined light blue cones of flame until the heat is turned up quite high. However, at low heat levels it doesn't blow out or do anything else annoying or scary. And it cooks food just fine!<img src=icon_smile.gif border=0 align=middle>

Now when I shut the valve at the tank with the burners still lit, it takes less than a minute for them to run out of gas in the lines.

A couple things we didn't nail down earlier.
<ul>
<li>Propane tank pressure can range from 1 atmosphere at something like -40*F to maybe 150PSI on a hot summer day. It's very dependent upon ambient temperature.
</li>

<li>Threaded connections in gas lines require a special gas-rated pipe tape, not just the usual water pipe stuff.</li>

<li>At a given temperature, the pressure is the same in all styles of tank.</li>

<li>Whether a particular container requires a pressure regulator depends entirely on the pressure needs of whatever appliance is connected to it, not on the size or type of tank.</li>
</ul>Let me know if you have other questions.

-- Leon Sisson

Sorry about the editing -- the preview feature is screwing up.

Edited by - Leon Sisson on 05/07/2003 12:30:59

Edited by - on

Earl Landers
Navigator

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USA
157 Posts

Response Posted - 05/07/2003 : 14:32:46

Just to muddy the waters a bit,
Camping world sells the following "High Pressure" hoses for running high pressure appliances directly from a "Bulk" tank.
<img src="http://www.campingworld.com/images/products/big/20000/24038d.jpg" border=0>

They can be connected to the Bulk cylinder using the following adapter.
<img src="http://www.campingworld.com/images/products/big/20000/24027d.jpg" border=0>

I have been using these adapters and hoses to fuel portable stoves and lanterns for years. I have a high pressure T, like this,
<img src="http://www.campingworld.com/images/products/big/20000/24024d.jpg" border=0>
permanently installled between the propane tank and the regulator in my travel trailer. The hoses have check valves to stop gas flow when they are disconnected, but they tend to leak. Available in 5 and 12 foot lengths. They are available here http://www.campingworld.com/browse/categories/index.cfm?deptID=3& catID=14

Earl Landers
'83 C25 SR/SK
"Gentle Spirit"

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tmhansen
Captain

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USA
397 Posts

Response Posted - 05/08/2003 : 01:33:11

It seems that every project I contemplate someone here is just a step ahead of me and asking all my questions for me. But I have a few more on this thread.

I want to do an installation like Ed's on Yahoo with a full oven, when I can find one like Ed did at a great price. I've thought about installing using the 6lb aluminum tank because I can fit it on my boat. OJ you say you wish you had got the 11 lb. Is this because it runs out too soon? Ed what is gas consumption like with your stove/oven? As I recall you were using the small bottles mounted to the rail in a clever pvc holder.

Todd Hansen
Fior Gra'
San Luis Obispo, CA

Edited by - on

folido
Deckhand

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Canada
11 Posts

Response Posted - 05/08/2003 : 07:18:38

I guess I will still be using my alcool pressure stove for some time. I used it every day for four months this last winter and it gave me great satisfaction in cooking meals and bread and cakes, etc. As long as I used a mixture of 40/60 of ethanol and methyl hydrate (abt 8gal.). I had to clean the burners one time only.
JGuy

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OJ
Master Marine Consultant

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USA
4382 Posts

Response Posted - 05/08/2003 : 11:09:43

<BLOCKQUOTE id=quote>quote:<hr height=1 noshade id=quote>
I've thought about installing using the 6lb aluminum tank because I can fit it on my boat. OJ you say you wish you had got the 11 lb. Is this because it runs out too soon?
<hr height=1 noshade id=quote></BLOCKQUOTE id=quote>

Todd, no, since they don't exchange smaller size tanks I just want to minimize side trips to propane fill stations . . .

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