The Steamboating Forum

I'm looking to convert a small 2 stroke lawnmower engine (or similar) to steam. At the moment I'm thinking of getting hold of an old gas cylinder or fire extinguisher for a boiler.

Anyone who has completed a project like this got any words of advice or offer any assistance?
I'm looking to keep costs to a min as I'm on a very tight budget.

AlbaSteamFan wrote:I'm looking to convert a small 2 stroke lawnmower engine (or similar) to steam. At the moment I'm thinking of getting hold of an old gas cylinder or fire extinguisher for a boiler.

Make sure that you obtain enough scrap wood/plywood to built a number of varying size coffins to accommodate your passengers when you are using said "pressure bombs". Don't know if the National Security Agency will try to get you as a terrorist, but you might want to have a lawyer on call.

Ron's sarcassim has merit, you should consult with some of the fellow steamboat men in your area about obtaining a suitable boiler. The steel used in the pressure vessels you mention would not be correct for fired service, and alternate paths to getting a safe boiler can be found.

Dear AlbaSteamFan ,

I know you want to cut costs as much as possible , and I am sorry if I'm pouring cold water onto your enthusiasm , but I don't think either of your proposed boiler options are feasible .

Fire extinguishers aren't designed to withstand more than a few psi , I'd guess perhaps 50-60psi , and certainly aren't expected to withstand heat .

A gas cylinder would certainly take a high pressure and quite probably withstand a high enough temperature ; so it MIGHT be a basis for a watertube boiler such as a Lune Valley , Illingworth , Blackstaff or similar type . But I have been told in the past that they are made from a high carbon content steel and are very difficult to weld , however I was told this some years ago and things may have changed a bit since then .

Another problem is that UK insurance companies require any boiler they cover to be to a design assessed by a qualified and approved engineer and I think it would be difficult to get the sort of design you are thinking of passed by such an assessment . It can also be an expensive business .

Unless you are a coded welder you will not be able to make a shell type boiler (eg : locomotive , vertical fire tube , Clyde etc ) yourself . This leaves watertube boilers and there are quite a few approved designs about . Unfortunately the materials needed , because they have to be of a high quality , are not cheap .

Although it is possible to cut costs a bit by calling in favours , getting skilled/talented friends to help , borrowing equipment etc it is not possible to cut corners in boiler design or manufacture . Doing so is definitely highly dangerous and quite possibly lethally dangerous .


Sorry for the bad news , Regards Edward .

Hey AlbaSteamFan

Yes the High Pressure gas cylinders will handle the pressure and yes they are hard to weld. They are great steel to use for waste oil burners or hydraulic supply tanks or wind chimes but don't try to make a boiler with one. The CO2 cylinders are hydro tested to 1500 PSI and typically run around 300 PSI depending on the ambient temperature. We use these cylinders for supply gas for the bulk air powered caulking guns we apply caulking with on buildings for waterproofing.

I have modified a few of them for dispensing various water proofing liquids as they make great bulk tanks. And they are just about indestructible.

If you want to try something for making steam try finding a steam generator like a Karcher or Landa oil fired burner that is used for heating high pressure water. We use these units to heat water from 190 to 300 degrees at 2500 PSI. They can be run as steam generators with a few added parts. https://www.google.com/search?q=Landa+H ... SICh1jvgUd

They are built to make continuous steam and would be a good place to start for something that already has safety features built in. I have found the units on Craig's list for as low as 500 bucks. They are 2200 bucks new and very easy to get parts for.

If you open one up it looks like a mono tube boiler or the first part of a LaMont boiler with a good size fire chamber. The coil starts as a water wall then laps as a three-layer pancake. Believe me the monkeys we have working here have tried every imaginable way to blow these things up and have only managed to blow the burst disk which makes a crap load of noise and will make you jump outta your skin but you will still be in one piece.

If you replace the burst disk with a steam relief valve you can avoid buying the burst disks. They are not expensive per say but the steam relief valve will reset and you can get back to experimenting. We have to use the disks for insurance purposes because when they fail the machine is supposed to be serviced before it can be used again. These things run in places where we are surrounded with curios pedestrians.

There have been two occasions when the coils have failed.

The first was on a job where the contractor shut off the water to the burners. The operator turned the water back on without letting the units cool and got quite a steam show. The steam was so hot coming out of the machine it melted the inside of the pressure hose which plugged the passage and then blew the coil because it was so hot.

The second time the monkeys blew the burst disk and instead of bringing the burner in for service they put a plug in where the burst disk goes and tried to finish the day. They did not; the burners flow switch was stuck on so the next thing to go was the coil.

So if you wanna play with steam start with something that is already designed to make steam with all the safety features already built in. They are very simple machines, very easy to maintain and damn cheep for what you can do with them.

Cyruscosmo

Seems like I'm back to the drawing board....

I will have to price up alternative (better thought out and safer) boiler options... It may mean my steam dreams go on ice for a few years if I can't get something cheaply. Will probably build the boat anyway and make some oars! Lol

Hi

Just a (late) thought in passing. Keep an eye on, or even place an ad on the SBA Small Ads site, assuming that your are a Member. There are boilers in garages that Members have bought and put on one side for when they have time to modify the boat, or for when they find just the right hull. Sadly, many just run out of time and those boilers go on sale for very reasonable prices. They are few and far between, and may not turn up when you want them, but keep on looking!

Regards

Pete

As far as the engine conversion goes, both 2 stroke and four stroke small engines have been converted to steam service with good results. Note that for every good conversion there are about 20 terrible conversions showing up on youtube and other media, so be cautious about the design you select. I have made conversions for both types of engine, ranging from 1 day conversions (simple and not efficient, but workable) to true high efficiency conversion suitable for 24/7 operation and steamboat duty. More details if you would like...