Gas fired engines

With the demise of coal will model engineers be able to build a gas, propane, fired engine, lots of advice on boilers and testing but what about a gas fired engine with a refillable/replacement tank.

Any fitting in my house involving gas and I need a gas safe certificate, we have a propane cooker, it takes the 'gas safe' plumber less than 15 minutes to check it over but costs £120.

Some councils have banned everything except cookers as long as  they are supplied by mains gas.

So, does building a engine with a gas fired boiler break any rules or regulations?

Edited By Cyril Bonnett on 16/03/2023 21:28:57

The WaterWorks Museum has a gas engine with hot tube ignition. Heated by gas of course!

Nearby, in another bay is another, but larger single cylider engine that is also town gas fuelled, but with electric ignition by an impulse magneto.

A lot of Technical Colleges had engines running on town gas, in the Heat Engines laboratories..

They all have to have pressure regulators in the feed line, or neighbour's cookers would fluctuate wildly every time the engine inhaled.

There are alot of gas fuelled engines on farms and places such as rubbish tips, running on methane from anaerobic digesters.

And in oil fields, many engine run on gas from the well, (i worked on one back in the early 60s ) rather than flare it off. Some are turbocharged and have very sophisticated control systems to manage the emissions..

Howard

I think the SFED testing procedure covers gas tanks. As long as you are outside or in a well ventilated space, it is difficult to build up a flammable atmosphere. Just be careful of spaces like boat hulls, propane is heavier than air (by quite a bit), so it can form pools in such spaces. Quite a few nasty accidents caused like that.

The biggest worry around small gauge locos which are frequently gas fired is people understanding the difference in pressure of butane and propane. A home made gas tank intended and tested for butane might not have been designed for the much higher pressures of propane which is fine until someone tries one of the 'better' mixed gas products (ie mix of propane and butane) that don't even tell you the proportions of each.

There's a blanket exemption in the gas safety regulations for self propelled vehicles, other than those used for hire or reward, so trains or traction engines would be in the clear (although the boilers would obviously still be regulated as pressure vessels).

It's less clear on stationary steam plants, the gas safety regulations only apply to installations connected to mains or "Gas Storage Vessels" (which is defined as refillable containers only), so using a disposable cartridge would put you in the clear.

Beyond that the manufacture of gas boilers is not in scope of the gas safety regulations, and instead falls under the Pressure Systems Safety Regulations, (as do other boilers)...

However making a gas connection other than between a gas installation and portable "Gas Storage Vessel" is in scope, so any pipework which isn't integral to the boiler design could be argued to be in scope of the regulations.

Making your own custom gas storage vessel would be again in the scope of the Pressure Systems Safety Regulations or the Carriage of Dangerous Goods Regulations, depending on if it is integral to the equipment or separate, both of which would be a lot of hassle to comply with, although not impossible if you're determined.

Edited By Jelly on 16/03/2023 22:26:42

In 5" I would be looking for the heating panels/burners from the old super ser room heaters as a start in experimenting with gas firing ! Balancing top air and bottom air to get it right could be a challenge, then there's the new riding trolley design to hide the 4.7Kg propane bottle. All good fun ! Noel

I would think that designing a burner to match the required thermal input of a boiler would be easy enough, anyone who can make an injector can make a Venturi burner.

The interesting bit is the relative controllability of gas boilers lending itself to water tube and finned heat exchanger boiler designs with much higher thermal efficiency and more responsive control characteristics, something which is restricted to blown pulverised fuel boilers when working with solid fuel.

There's also oil-firing which has many of the advantages of gas without the need to store the fuel under pressure, the Doble Steam Car used an oil fired water tube steam generator to propel a 2 ton vehicle to 110mph in 1909!

The model boat guys have been building gas fired engines for years so the tests they have to put their tanks through would apply to other club members using gas for a loco etc. Can't remember the test pressure(s) now but it's a lot higher than most copper boilers to allow for the gas expanding if your model is sitting in the sun and for the particular gas

From memory I think a figure of 450psi for propane as a test pressure ! But with say a 5" loco why build a gas tank when you can hide a 4.7Kg bottle in the riding trolley - with it's regulator. BUT the sweet smell of burning coal will be missing from the hot oil and steam flavour !

If all you want is a self propelled loco then put a small honda on railway wheels, or build something like a high effiency challoner or try to make Hush Hush or leader work but if you want it to look like something from over 100 years ago that people recognise as a steam loco then the mold is made ! Noel.

Would it be any more complex or regulated than using a gas bottle on a barbecue or workshop blowtorch or camping stove. IE no regs other than pertaining to the gas bottle itself?

Those disposable gas torch bottles would seem to be about the right size for mounting in a loco tender etc and would get around having to make your own bottle and get it tested etc.

EDIT Or as Noel posted simultanously, one the small 4.7kg barbecue gas bottles in the larger locos.

And is coal going to disappear completely? It may be allowed for such small "heritage" applications. At a price of course!

Edited By Hopper on 17/03/2023 10:27:06

Edited By Hopper on 17/03/2023 10:28:40

This web page shows it has been done, with detail on burner design:

http://ibls.org/mediawiki/index.php?title=Marty_Burners.

Martin

People don't realise just how much heat is liberated in a 5"g loco firebox. Even a medium size loco working fairly hard is over 15kw. Getting this amount of gas to burn inside the confines of a model firebox is not trivial. Super ser heater is much bigger in area for a much lower heat output. You need lots of small flames to maximise the flame surface area relative to the nozzle area.

Just checked and current club test is 400psi for refillable tanks upto 250mls, copper or brass either pure butane or upto 40% propane mix

Unlikely to be banned, more likely to become unobtainium if the only customers are Model Engineers, who buy very little. It's already the case that steam coal is hard to find, and the UK is relatively lucky in that regard. At least it's available here in small bags, there must be many countries where it's special import only. Many engines seem to run on alternatives like barbecue charcoal and smokeless fuels.

Not a new problem. GWR engines outperformed their northern rivals because the GWR connected with Welsh collieries producing the best steam coal in the world, whereas northern coal was noticeably dirtier, burned at a lower temperature, and had a lower calorific value. The need to burn poor coal or wood can force major design changes on locomotives. It's not just that the fireman has to shovel extra fast into a big firebox.

I have an old mag where LBSC moans about finding impossible to buy good steam coal after WW2. It's because most of Britain's best coal was exported to pay off debts, whilst homes could only get the notoriously bad 'Nutty Slack'.

I can't see running on gas outdoors being a problem unless someone foolishly causes a major incident. Gas burners are well established technology. Running an engine on Hydrogen might be controversial though!

Dave

Well that's would certainly be one way to force people to move on from copper!

(For those not aware, copper is particularly susceptible to hydrogen embrittlement due to alloying non metals in most grades, a particular grade of pure deoxidised copper is suitable but still doesn't perform all that well. Much experimentation is ongoing as to just how much H2 can be blended with Methane before it becomes problematic, with a view to altering the composition of mains gas.)

About 30 years ago I visited LALS the Los Angeles Live Steamers just the other side of the hill from the famous Hollywood sign and they were mostly if not all running on gas for fire safety and probably coal not being much in evidence in their climate. It is not for aesthetics that the loco chimneys in wild west movies were an inverted bell and the tender piled high with wood not coal.

I have converted to propane in Australia , the governing body here is the AALS for model loco.s the have rules on propane firing , the completed setup has to be passed by a licenced LPG gasfitter however every state in Australia have different rules just to confuse everyone, i only run on one to two psi ,so the whole instalation is low pressure from the gas bottle.

Noel Shelley I used [Marty's burners] look it up ,the drawings are there for anyone interested and i have eight burners in the firebox ,they work a treat and are easy to make.

Phillip, what size/shape is your firebox?

Further to Bazyle’s comments , as I understand it , Train Mountain Miniature Railway operates about 30 miles of 7.5” track , and all of their steam powered locomotives are gas fired ! .

I just do not understand how they have done it safely over many years , yet in the UK , anyone suggesting gas firing is made to feel like a lunatic , a mentally affected moron! , and then you have the insurance brigade ,

There are many benefits to propane firing locomotives , the Model Engineering / Rail fraternity should welcome the system and encourage its application, and the Insurance Industry should drop its objection and be more acceptingof it , even learn from those overseas experiences.