Butane vs. Butane/Propane Mix for Roundhouse Locos

H

hobbyfossi201

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Good Morning!

I´ve heard that Mix has different burning characteristics than pure butane. Roundhouse states in their manuals that the mix is ok when pure butane is not available.

What does this mean?
Do I have to expect problems on the boiler when always using the Mix?

Please share your experience and opinion, as I was not able to find the proper information on the web.

Thank you in advance

Klaus
 
Re:Butane vs. Butane/Propane Mix for Roundhouse Locos

Propane is alleged to have a much higher preassure than butane and is alleged to be a hotter burner. Thus I feel safe to use it in the Winter (when very cold) but would use Butane Only Gas in the summer. i am quite happy to be shot down in flames over this one, but this has always worked OK for me over the last 28 years.
JonD
 
Re:Butane vs. Butane/Propane Mix for Roundhouse Locos

I don't envisage any problem, you'll most likely find you need a slightly different setting on the gas valve and may have to adjust it more or less frequently during a run.
A few words of caution which shouldn't be cause for concern with, amongst others, current production Roundhouse gas tanks.
The gas pressure in the tank depends on temperature and Butane/propane mix can reach far higher pressure when warmed than pure Butane, I quote from the maker of a gas tank from one of my steamies.
“The tank is substantial enough to handle a Butane/Propane mix, providing that the gas tank is not mounted adjacent to the boiler and getting too hot. You can always tell when a gas tank is getting hot and over pressured - the burner starts to surge and makes a whoosh, whoosh sound, at which point you either turn the gas out, or ---- take to the hills!"

In cold weather Butane may have insufficient pressure for satisfactory steaming, Butane/Propane is ideal in winter or whenever the ambient temperature is below around 100C for most locos designed to run on Butane. Also the tank cools as the pressure drops due to usage of the gas, cooling the tank further. This is one reason why the gas valve may need adjustments during a run.
Some larger locos have water baths round the gas tanks to help maintain a steadier pressure by minimising the pressure drop due to cooling. I believe some even have a live steam takeoff from the boiler to help keep the water bath warm, but not too hot.
 
Re:Butane vs. Butane/Propane Mix for Roundhouse Locos

I think you will find that the larger B & Q stores stock it in their tools section!!
 
Re:Butane vs. Butane/Propane Mix for Roundhouse Locos

jetomlin said:
I think you will find that the larger B & Q stores stock it in their tools section!!
Click to expand...
I also find my local Focus DIY usually have some in stock. Not particularly cheap but they do have a 10% discount for old fogies like me seven days a week.
 
Re:Butane vs. Butane/Propane Mix for Roundhouse Locos

see it less often in Q&B now and my local hardware shop say Taymar have stopped doing it
 
Re:Butane vs. Butane/Propane Mix for Roundhouse Locos

owlpool said:
see it less often in Q&B now and my local hardware shop say Taymar have stopped doing it
Click to expand...

Focus sell the "GoSystem" brand of Go Gas Limited.
 
Re:Butane vs. Butane/Propane Mix for Roundhouse Locos

Thank´s Guys for giving me your advise.
I thought using the Butane/Propane Mix might damage the boiler; now I´ve learnt that we´re focused with different pressure.

regards
Klaus
 
Re:Butane vs. Butane/Propane Mix for Roundhouse Locos

Be careful with the butane/propane mixes because of the higher pressures brought on by propane. The best benefit of the mix is that it will still turn into a gas at lower temperatures whereas pure butane will not. The magic number is around 50 degrees F. The presure increases as the amount of propane in the fuel increases, so you should look for the lowest percentage propane available [our locos fuel tanks may not be capable of handling the much higher pressures with more higher percentages of propane].

In the US, we can get a 90/10 and sometimes 80/20 [butane/propane] mix at camping supply stores. The brand most often available is PRIMUS [they make small camp stoves too].

Does anyone know highest percentage of propane our models can use safely?

Thanks,

Will
 
Re:Butane vs. Butane/Propane Mix for Roundhouse Locos

I understand B&Q have stopped stocking butane and only have what is left in stock.Some manufacturers sell what seems to be pure butane but if you read the labels you will find this is not so,they're usually mixed gasses.
 
Re:Butane vs. Butane/Propane Mix for Roundhouse Locos

Just for clarification, flame temperatures for butane and propane are, to all practical intents and purposes, the same.

What does differ is the fuel/air ratio, calorific value, boiling point and storage pressure.

Propane Air Fuel Ratio = 23:1
Butane Air Fuel Ratio = 30:1

Propane Calorific Value = 95 MJ/m3
Butane Calorific Value = 121 MJ/m3

Boiling point of Propane is approximately - 42°C
Boiling point of Butane is approximately - 2°C

At ambient temperature (i.e. 15 degrees Celcius), propane and butane cylinders would be at the the following pressures:
Commercial BUTANE 2BAR (28psig)
Commercial PROPANE 7BAR(100psig)

It's a subject that has raised it's head many time in the past on GSM.

Most important thing to consider is that, if the manufacturer says you can only use butane, use butane only!

The LPG (Liquefied Petroleum Gas) sold in this country is subject to certain British Standards and are sold primarily as Commercial Butane, normally in blue cylinders, or Commercial Propane, normally in red cylinders, both of which contain elements of other gases, and as mixtures of the two. Don't take colour coding as a given though, there is NO agreed standard!
 
Re:Butane vs. Butane/Propane Mix for Roundhouse Locos

I have used mixed in my locos with no problems although i do try to use butane when i can get it. My local B&Q don't sell it anymore and neither does Screwfix. I've been told to up end mix cans a few times to mix the gases up otherwise you get pure propane.
 
Re:Butane vs. Butane/Propane Mix for Roundhouse Locos

This topic comes up more than any other in the live steam section..........Well except for what water should I use! As has been said the burning of the gas is not the critical bit, gas tank storage capacity and pressure is what the main problem is. propane reaches higher storage pressures for a given volume at the same temp. so some of the storage tanks were designed to hold butane only and have a overpressure rating to suit butane at the highest temp's. the problem occur's when you use a mix because now the propane part wants to take up more space hence the pressure goes up possibly enough to go above the saftey rating of the tank and Boom...............I have to say it's unlikley but if it says Butane only on the tank thats what I shall use!! You can check with the manufacturer of your Loco and see what they say. I know Accucraft recalled some gas tanks for this very reason..............So if in doubt use the safe route. try googling BLEVE and see what exploding gas tanks look like.................

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Re:Butane vs. Butane/Propane Mix for Roundhouse Locos

minimans said:
try googling BLEVE and see what exploding gas tanks look like.................
images
Click to expand...
and in a past life (my job/career for 30 years before the dreaded 'R' word!) I was involved in doing that on purpose, but under controlled conditions, not something you would want to do accidentally!
 
Re:Butane vs. Butane/Propane Mix for Roundhouse Locos

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I can use butane/propane mix in this little fellow, but I have also a meths tank/meths burner which I can swap over to.Far more safe if there are other engines are in steam. Alyn
 
Re:Butane vs. Butane/Propane Mix for Roundhouse Locos

For Info:-
Screwfix stock butane canisters and 80:20 mix gas canisters both with EN 417 screwthreads.
I have just bought some at their shop this morning, don't know if they'll deliver though.
 
Re:Butane vs. Butane/Propane Mix for Roundhouse Locos

I have been using gasmate butane/propane 95/5 without any adverse effects.
 
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