M2 Burner to Propane Experiment

I have been interested in converting several of my M2 burners to propane and finally got around to experimenting with it. Here is what I found:


Summary
The first phase of the Great M2 Burner Experiment is finished. The preliminary conclusion is that the six armed burner in the M2 burner cannot be run off of Low Pressure Propane (LP Propane). LP Propane is 1/2 PSI and HP Propane is anything higher. It also cannot be run off of 10 PSI HP propane. Propane powered tar pots and other equipment that is more robust than a barbeque grill or turkey cooker uses as much as 40 PSI pressure. That kind of pressure might work.

M2 burners have gotten a lot of bad publicity. I can see that if you treat them according to the TM, it is inconvenient. You have to fuel and light them 50 ft. from everywhere and, if I am interpreting the instructions right, you have to carry it to the MKT running on low. I would shut it off after getting it hot, insert it in the MKT and relight it. That whole process took 10 minutes which would be 10 minutes of down time if a burner ran out of fuel in the middle of cooking.

I have used Coleman lamps and stoves for years, decades, and do not consider them to be too dangerous. I know that I have read on the web site about SS guys doing a lot of far more dangerous things with their trucks than using an M2 burner. Still, propane would be preferable for most civilian uses.

Here's what my experiment looked like:

The Experiment
I took the generator off of an incomplete M2 burner and cut off the valve/orifice end. Next I cut 1/2 inch NPT threads on the pipe. I bought fittings and an LP regulator at Home Depot. Here is the arrangement I came up with (second picture)

Expecting to need to run 2 M2 burners I bought a regulator with a double hose on it and plugged off one branch.

I connected up the arrangement on my good M2 burner with the generator removed by temporarily wire tying it to the pressure gauge/pop-off valve to keep the orifice inserted properly (3rd picture)

The results were dismal. The flame barely produced any heat. Next I took the 10 PSI regulator from the Bayou Classic turkey cooker and tried the same experiment. This time there was a slight, I mean 2-3 MPH, wind blowing and I could not keep the burner light.

I looked around the Internet and found one possible combination that, with enough money, should work quite well. Here is what I found at Bayou Classic Cooking:

http://www.bayouclassiccooking.com/30hiprvawi48.html
A preset 30 PSI regulator with 48 inches of hose for $27.99 (4th picture)

http://www.bayouclassiccooking.com/10quot-cast-iron-banjo-burn10.html
A 10 inch Banjo Burner for $47.99 (5th picture)

These 2 parts are designed to work together and should do an excellent job of replacing the gasoline powered M2 burner.

Back to the original plan, I would still like to make use of the existing burner in an M2 unit. I believe my test arrangement would work with the 30 PSI regulator. If someone has the $$ to pickup where I left off, I would sure like to hear from you.

What you suggest as shutting down the M2 then bringing it into the range and relighting it is a bad idea. I've seen them "go bad" first hand, and when you dont follow the instructions exactly, bad things happen. The cooks didnt call them the "M2 Bomb Unit" for nothing, and the Army has replaced every one of them with the much safer and easier to operate MBU.

One of the first problems you have is using the original orifice for propane. You will probably have to drill out the hole in the end of the orifice to get enough gas to make the burner burn properly. Or either close it off some to get enough pressure. I don't remember which right off the top of my head. It's like using a natural gas orifice with propane. They aren't interchangeable.The one I did used a regulator/hose combination that already had an orifice on it. I tack welded a reduction bushing to the air shutter to accept the threaded orifice and it seems to work pretty good. I haven't measured the actual heat output but it did a great job with one of the large square pans on it frying chicken!!! Around here Lowes and Home Depot both carry them. I'll try and get a part number if you want to see if you can find one. I think it is made by Bayou Classic as well but it isn't the one you have pictured. The one you have pictured will work if you can find a propane orifice that has the 3/8" flare fitting to mate up with the end of the hose you have. I hope I haven't muddied the water too much but that is what I have found in my attempts at conversion.

Hey one other thing, I wouldn't be burning that thing too much with the old fuel tank still on there. If that thing has ever been used you might have some gas residue or have the metal impregnated. After it gets heated up you might have a large problem if it starts making any vapor!!!!

There is a nice article at Seabee Cook that explains the conversion of the older M1937 burner to propane that should be usefull for this conversion. I sold off my M2 burners a while back when I got a bunch of MBU's, so I have never tried a propane conversion.

See:
Converting an M1937 Fire Unit to Propane

The author of the above referenced conversion used (among other parts) a 1/4" npt male thd. brass gas orifice with hole sized to a #57 numbered drill bit and a high pressure regulator.

I have used the banjo burners before in other applications and they do put out the heat... You can pick them up at Agri-Supply with a hose and regulator for less money than from Bayou Classic.

Good luck.

I did the same thing for two of mine and now have them working. I will get some pictures posted as soon as I can get them off of the camera. First try was a 10 psi regulator attached to the stock burner and neck. This worked but gave off to little propane and I ended up with a nice campfire looking flame that does not provide enough heat. I then tried the 30 PSI regulator and hose set up with the stock gear but it started to put flame out of the valve and around the hose. Killed that experiment quickly. I am now using the complete 20 psi set up from a Bayou Classic SP-10 high pressure cooker set. The burner unit will bolt in to the set up at the same spot and provides good heat. Using this set up I was able to heat both the ten and fifteen gallon pots to boiling and cook chicken. I am experimenting with using one for a smoker and it works but keeping a constant temperature has been difficult. I used these as they are on the shelf at my local Lowes and set me back about $45 each. The safety factor of using a complete and tested system is worth the money to me and now I just need to get a third set up and try the larger 30 psi set up.

Emmado22, Your point is well taken. My wife, who was helping me with the experiment, and I talked about all the things that can go wrong with a stock M2 burner and we have decided to definitely pursue the propane conversion and forget using the M2s that I have.

MitchG, I think that I need to open up the orifice. Going from propane to natural gas requires increasing the size because natural gas has less energy per unit of volume than propane, just like going from diesel power to gas. Likewise, I believe that gasoline in vapor form has more energy than propane, so an orifice set up for gasoline probably needs to be opened up.

CGarbee, Thanks for the reference to the article in Seabeecook.com. One thing that surprised me was his estimate of 50,000 BTU output of his M1937 burners; I thought that it would be more, but I think he knows what he’s talking about. They are very similar to M2 burners and for the same reasons he cited, more even heating, I would like to use mine. Plus I already have all the heat shields.

David Jarvela in the article used up to 26 PSI with a custom orifice, so what I think I will try next is get a 0 – 30 PSI regulator and drill out the orifice with a #57 drill bit, as he did. I like the idea of using the original valve and orifice, if I can make it work (I have to justify to my wife the $49 spent on the 1/2 inch NPT thread die). If it works it will be the cheapest solution and I intend to do a total of 6 units.

Well, ‘gotta get back to the job hunt so that I can afford this. I finished my MBA and the student loan checks are ending.

Arlyn

I did the conversion as shown on the Seabee cook page and it worked ok. For my other ranges I simply bought the on sale fish fryer at bass pro did not install the legs and just slid it into the field range on a scrap piece of 1/4 Al tread plate, did it with a turkey fryer burner form Aldi's also. Both work great.

The MBU's that replaced the M-2 burners put out between 14,000 and 61,000 BTU/HR. I can bring a 15 gallon pot of water to a boil in half an hour with the setting just past half way, which would be about 40,000 BTU/HR. Higher elevations and colder climates could require more energy than I'm using, YMMV.

For my other ranges I simply bought the on sale fish fryer at bass pro did not install the legs and just slid it into the field range

Click to expand...

I converted a field range/oven using this same method. I drilled a small hole just above the sliding doors to accommodate the fish fryer thermometer.
You have to keep an eye on the temperature, but you can tweak the regulator until it becomes fairly stable. Through experimentation, I ended up dropping the chain suspended plate 4". You can bake a biscuit golden brown, and not scorch the bottom.

Well, here are the photos of the conversion that I did on my M2 burners. I have left them looking fairly stock but have removed as much of the extra / unnecessary gear as possible. To try and make sure that there were no issues with the fuel tanks I opened up every port on them and let them sit for a couple of days before using.
Pic 1 is the starting point of a stock burner.
Pic 2 is a fully stripped down frame
Pic 3 is the burner I used to convert over to propane
Pic 4 - 7 are of the assembled burner with the Bayou Classic propane set up. This bolted right in in place of the burner assembly for the gas.

Have converted the M 2 burner to propane following Mr. Jarvela's guidelines. Going to try it out on biscuits tomorrow.

Makes me wonder where is the party?

Baked bread in my M 37 oven at noon today. Not bad for my first in this oven.

An orifice bored out to size 57 drill bit, and high pressure LP gas at 30 psi worked great. Also used a needle valve to fine tune flame. M 37 manual says green flame gives best results. Unfortunately, this set up only gives off blue flame, which may degrade burner.