propane question

[JohnHudak]

Hi everyone, I'm thinking about using two of the 1lb camping (short) throw away propane bottles to power the 3/4" B&O 0-4-0..
This locomotive is small enough to carry in the trunk of a car, in which case I wouldn't want to carry the larger 5lb bottle full of gas..
I'm thinking of using two of these Mr Heater adapters https://www.mrheater.com/1-4in-male-pip ... hread.html
And making a manifold that will connect the two bottles together, to act as one.. From that manifold, I'll put another adapter that will mate up with my regulator, which will have one line going to my burner manifold..
Any issues with trying to connect two gas bottles that may or may not have the same amount/pressure in them?
Thanks.. John

[FLSTEAM]

When you connect the two together any difference in pressure will equalize.

John B

[ChuckHackett-844]

As John said, the two cylinders will equalize and equal amounts of gas will be drawn (assuming the tanks are at the same temperature).

Note:
a) I would add a shutoff on each bottle. That way you can swap bottles without killing the fire/pilot (assuming the other bottle has a bit of propane in it). This shutoff would also allow you to draw one bottle totally down before turning on the other one (assuming that your rate of gas consumption does not freeze the one tank).

b) Keep in mind that you have to keep these bottles vertical otherwise you run the risk of flowing liquid to your regulator - bad, at the very least it will freeze (due to expansion of the liquid to a gas within the regulator), or, worse, get liquid as far as the burner.

[ChuckHackett-844]

Also ...

Be sure to use a regulator designed for fuel gas - not an air regulator. The reason is that an air regulator has a vent which is bad near open flame!

[JohnHudak]

Thanks for all the replies, all great advice..
Re: Those valves I listed, when I’m installing the tanks onto the manifold, will gas flow out the other valve (assuming I don’t have shut offs)?
John

[ChuckHackett-844]

Re: Those valves I listed, when I’m installing the tanks onto the manifold, will gas flow out the other valve (assuming I don’t have shut offs)?

I assume yes, because it does not mention a check valve and normally, a grill/whatever that uses these would not need it to have a check valve (i.e.: they are normally only connected to one tank).

[Harold_V]

I suspect that even two of those tanks operating simultaneously will have icing problems, reducing fuel delivery to the point where steam pressure can't be maintained. That might be avoided if heat is provided to keep the bottles from icing.

H

[JohnHudak]

I suspect that even two of those tanks operating simultaneously will have icing problems, reducing fuel delivery to the point where steam pressure can't be maintained. That might be avoided if heat is provided to keep the bottles from icing.

H

Harold, we’ll find out.. All I know is that we used to take one of those tabletop propane grills tailgating, and they use a single bottle of what i’ll be using.. That little thing cooked us a lot of food over several hours, and I don’t ever remember it slowing down...?
The total burner length for that grill was probably 14” long, with holes on both sides..

[rkcarguy]

Icing shouldn't be an issue as long as it's warm enough and wherever the tanks are has adequate ventilation with warmer air. Propane loses it's pressure and stays a liquid below 20*F so icing is going to be dependent upon the ambient temperature and demand placed on the tanks. Propane forklifts for example circulate engine coolant through the regulator to keep it from icing up. Likewise the tanks will vent when they get too hot.
There are temperature/pressure charts online for propane.

[ChuckHackett-844]

I suspect that even two of those tanks operating simultaneously will have icing problems .... That might be avoided if heat is provided to keep the bottles from icing.

If by this you mean 'heat' above ambient temp - It is never advisable to heat a propane tank! Inattention/malfunction can lead to catastrophic propane gas release (burst disk opening or even tank rupture) ... imagine the fun (not) of all the gas in those tanks rapidly forming a gas cloud around you which then ignites.

Best is to be sure air can circulate. At most an ambient temperature water bath to just give up heat to the tanks.

If the tanks are freezing, you are just drawing too much gas too fast ... change the setup to one that provides more surface area (more or larger tanks) ... it's not worth your life ...

[ChuckHackett-844]

....
Propane forklifts for example circulate engine coolant through the regulator to keep it from icing up.

Forklifts (and generators, etc.) heat a device called a 'vaporizer' not the tank. This is because they require large amounts of gas. Liquid is fed to the vaporizer, heated to convert it to a gas and the gas is then fed from the vaporizer to the engine. There is a very small amount of liquid/gas in the vaporizer which is why this is safe.

Likewise the tanks will vent when they get too hot.

That prevents the tank from exploding and then igniting ("BLEVE" - Boiling Liquid Expanding Vapor Explosion) but it still releases a dangerous cloud of explosive vapor ... near a firebox ... not good ...

[rkcarguy]

....
Propane forklifts for example circulate engine coolant through the regulator to keep it from icing up.

Forklifts (and generators, etc.) heat a device called a 'vaporizer' not the tank. This is because they require large amounts of gas. Liquid is fed to the vaporizer, heated to convert it to a gas and the gas is then fed from the vaporizer to the engine. There is a very small amount of liquid/gas in the vaporizer which is why this is safe.

Likewise the tanks will vent when they get too hot.

That prevents the tank from exploding and then igniting ("BLEVE" - Boiling Liquid Expanding Vapor Explosion) but it still releases a dangerous cloud of explosive vapor ... near a firebox ... not good ...

Sorry, the "vaporizer", I forgot my propane part nomenclature. Propane does have it's drawbacks. Too hot and the tanks vent, too cold and there is no pressure(propane remains a liquid). We have to keep our forklifts indoors most of the time because of these issues. Had a few days of 7*F a few years ago and NOTHING left outside would run. No pressure in the propane tanks and the diesel forklifts fuel was like Jello.
Good point, one would be wise to vent their PRD such that it exits out the back of the tender is about the best you could do?