Early Roundhouse spirit fired locos

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big-ted
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Early Roundhouse spirit fired locos

Post by big-ted » Sun Jun 27, 2021 8:12 pm

All,

Those following my general thread will have seen my efforts to build up a very early spirit fired Roundhouse Dylan:

https://gardenrails.org/viewtopic.php?f ... 90#p158819

I've given it a couple of runs now, & learned the cheap, generic lamp wick material didn't work. It tended to burn, which then sealed the ends & meant it only efficiently wicked the fuel for a couple of minutes before I would have to fluff it up again to remove the sealed ends.

I've now got some proper ceramic stuff, which works much better but, if anything, the flames are still a bit large (over an inch at times with the burner removed from the loco) despite being packed much tighter than what I would call the "loose push fit" called for in the Roundhouse spirit firing guide.

How long do owners of these locos get out of a single fill? I was finding that a single fuel fill would only get a few minutes of running once pressure was raised, & there was a lot of water left in the boiler at the end of the run. Based on this I took to refilling the burner halfway through the run. This seemed ok, until I ran the boiler dry... Fortunately I caught it & was able to remove the burner before any damage was done.

Which brings me to my next point. Is there a way to extinguish the burner if one needs to? It's pretty sealed within the firebox, so blowing it out doesn't seem like an option. I wondered about sealing the filler tube to create a vacuum, but I guess the overflow means that won't work..?

The firebox also makes it impossible to lubricate the eccentric valve gear on the rear axle without inverting the loco. Any tips here?

I'm also a bit nervous about leaves & other debris getting sucked up into the burner & catching fire? Any cause for concern?

Any tips or experience very much appreciated!

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Re: Early Roundhouse spirit fired locos

Post by big-ted » Mon Jun 28, 2021 2:04 am

A bit more detail having just done a test run on blocks....

Pressure is raised in 5 minutes (seems reasonable. Comparable to my butane Lady Anne, although we're currently in the middle of a 40 degree heat wave...)

I then get 5 minutes of excellent running, before pressure drops to less than 20psi & the loco struggles to turn over. But at least one burner is staying lit far longer (~ additional ten minutes) as it stays hot with pressure around 5-10psi.

If I refill the burner pressure comes back up & I can run for a few more minutes, but now the long period of low heat risks water running out before fuel.

Seems something isn't quite right. Is there a way to get higher heat for longer & then run out of fuel more abruptly?

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Re: Early Roundhouse spirit fired locos

Post by TonyW » Mon Jun 28, 2021 10:28 am

Bio-ethanol may be your friend. It is an excellent substitute for meths and is available in the UK from DIY sheds where it is sold as patio heater fuel. I use nothing else these days as it burns hotter and without noxious fumes.

I can't help with run times, other than to say that I have had my Dylan in steam continuously for eight hours. A water top-up system is needed to do this, of course, and a dose of fuel goes in when I top up the water. The top-up system also avoids the need to extinguish the burner (which needs a huge pair of lungs to do) as the boiler can be refilled.

And yes, there is no way to oil the back axle eccentrics without inverting the loco ... unless you have a "pit" (hole in a baseboard) that can be accessed from underneath.

Just reading about stiff points on your other thread. Valve setting on these locos can be fiddly and getting it running on air is no guarantee it will run on steam. The culprits are the eccentric arms which expand (grow longer) when they get hot, so upsetting the valve timing. I get them running on air then give each valve spindle half a turn anti-clockwise (I think!) before steaming.
Last edited by TonyW on Mon Jun 28, 2021 1:48 pm, edited 1 time in total.
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Re: Early Roundhouse spirit fired locos

Post by GTB » Mon Jun 28, 2021 1:12 pm

big-ted wrote: Sun Jun 27, 2021 8:12 pm
Which brings me to my next point. Is there a way to extinguish the burner if one needs to? It's pretty sealed within the firebox, so blowing it out doesn't seem like an option. I wondered about sealing the filler tube to create a vacuum, but I guess the overflow means that won't work..?
I've seen the local G1 mob with a gizmo that is basically a miniature CO2 fire extinguisher. As far as I know it uses the same CO2 cartridges that are used in carbonated water dispensers. Not seen it used on a Roundhouse style burner/firebox, but can't think of any reason it wouldn't work.

The Oz supplier is Argyle Locomotives, but I think they are also used in the UK. Not cheap, but neither are replacement boilers.......

https://argyleloco.com.au/product/argyl ... inguisher/

Regards,
Graeme

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Re: Early Roundhouse spirit fired locos

Post by -steves- » Mon Jun 28, 2021 1:47 pm

Great idea with the CO2, going on from that, maybe a bicycle inflator that runs on CO2 might be far cheaper although some adaptation may need to be done to get it to "fire off" so to speak as usually they rely on the forcing it onto the valve to help it set off as well as a press of a button. :dontknow:

Maybe this kind of thing? But please do look into how they are set off as I am pretty sure they rely on force onto something, so maybe an adaptor for the chimney or something?

https://www.amazon.co.uk/Weldtite-Valve ... 8964&psc=1
The buck stops here .......

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Re: Early Roundhouse spirit fired locos

Post by GTB » Tue Jun 29, 2021 8:13 am

GTB wrote: Mon Jun 28, 2021 1:12 pm I've seen the local G1 mob with a gizmo that is basically a miniature CO2 fire extinguisher.
Knew I'd seen them somewhere on a UK suppliers website.............

Mike Darby at Chuffed 2 Bits sells a version of these mini extinguishers.

http://www.chuffed2bits.com/page9.html

Scroll right down the page, as it's third item from the bottom.

Graeme

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Re: Early Roundhouse spirit fired locos

Post by big-ted » Tue Jun 29, 2021 5:15 pm

Some great input here. Cheers chaps.

Re:C02, this is a great suggestion. Especially as I tend to keep a couple of the 32g canisters on hand to carry with me whilst mountain biking.

Tony, I had wondered if something was expanding and causing the discrepancy in running on air vs. under steam, but my mind was assuming something was binding when hot. It never occurred to me that the timing might be thrown slightly off. I've adjusted the valve rods half a turn as if the eccentric arms were slightly longer and we'll see what difference this makes. I know how to go back if it gets worse!

I also have another theory on why pressure would suddenly drop part way through the run. I had a small leak from the boiler level plug on the back head. With water above this level (as it is when you fill the boiler then remove 30ml) water would very slowly drip out, but I didn't think of it. I wonder if, once the water level drops below the level of the bush, steam is able to leak out much quicker, causing the difficulty maintaining pressure? Either way, a leak obviously isn't a good thing, so I've replaced the gasket and dressed it sealant (I don't use the level plug since it's so hard to access with the cab on).

Will update once I've had a chance to run it again. At the moment my only option is out on my balcony, and given the current heatwave, the last place I want to be is out on my balcony leaning over a hot steam loco...!

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