spark arresters

[fred55]

I have a 7 1/4 Briggs boilered loco which burns coal. I'm building a track "in the bush" soon and a spark arrester will be essential.
What types are there and what are the pros and cons?
I would prefer something out of sight and definately not a bear trap or balloon stack
Pete

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[drjohn]

I am also thinking about such a device as my chest keeps getting multiple burns!

I am looking at making a tube from mosquito screen to go from the petticoat pipe to the blast nozzle inside the smoke box, but others may have better ideas. Like you, Pete, I don't want an auspicious piece of rubbish on the top of the chimney.

Cheers

DJ

[brozier]

Hi Pete,

I've seen some designs for a mesh spark arrestor within the smokebox, which from the side goes diagonally from front bottom near to the smoke box door (with enough space to remove ash under it) to rear top near to the boiler.

The blower and exhaust poke through the mesh and so exit on the "clean" side of the mesh. This gives a much larger surface area than say just a disk of mesh in the funnel!

You have to be quite careful as getting the draughting wrong can ruin a decent loco....

Cheers
Bryan

[smallbrother]

I rolled some stainless steel mesh into a tube and secured it with a jubilee clip to the petticoat pipe. This was my first very simple loco which had an uncluttered smokebox.

I would love to see a photo DJ if you can get something inside the Simplex.

For my Polly, I use a mesh disk held above the chimney on legs which spring into the chimney. Not pretty.

[jgb7573]

We had a chat about these a while back (see modeleng.proboards.com/index.cgi?action=display&board=general&thread=3730&page=1). This may be helpful.

[steam4ian]

G'day Pete

You make me sorry I didn't take a photo when cleaning out the smokebox of W22 at PRR recently.

This loco has a cylinder of mesh around the blast pipe up to the peticoat and a mesh disc over the bell mouth of the peticoat. This seemed to work well enough without clogging. It looked like it came with the loco.

The Coffee Pot has a narrow peticoat which extends well down into the smoke box, it is a modification on the 1906 original. A cylinder of mesh around the peticoat catches the sparks.

So there are prototypes for DrJ's suggestion.

A couple of locos at my club use oversized tea strainers supported above the funnel. These have the advantage of being easily removed for cleaning and aesthetics. The don't have to fill the funnel opening just catch the blast. Their draw back is their appearance and the fact that they catch cylinder oil which clogs them.

Regards
Ian

[fred55]

I tired the search but didn't find that post.... ::)thanks.
My preference would be for a flat screen across the firebox with the blastpipe poking through, but it was suggested that the "vortex" would be disrupted resulting in loss of steaming. (as brozier mentioned) Mesh tube between blast nozzle and petticote are supposidly too restrictive, and anything on the output side would be blocked with oil.
I'd love to see some pix of peoples efforts
Then there's the ashpan to think about,
Pete

[jempc]

You may be interested in this...
www.steam-loco-design.co.uk/spark_arrestor.html

[fred55]

Very interesting setup jempc/ The linked thread showed expanded mesh of 5mm, Dr J is talking insect screem 1mm app, what size particles constitute a fire hazard?

[drjohn]

The bits that burn holes in my chest and hair would certainly pass through 5mm mesh - all I want going through is the hot gases - still not implemented it but will report once I've got round to it.

DJ

[jgb7573]

A couple of pictures of the arrester in my 5" gauge Hunslet. It's best to fit this when everything is cold as it involves feeding it in to the smokebox, large end first, letting the bottom end drop between the tubeplate and the blastpipe, lifting the large end back up around the petticoat pipe and then dropping the bottom end to sit on top of the blast pipe. Oh and you have to have it the right way round as there's a dent in the gauze to make space for the dart on the smokebox door.

[jgb7573]

And here it is in place

[digger]

That spark arrester looks the part, I have at this moment on my desk a 'pen tidy' that is just waiting to be modified into a spark arrester, for a re-built Merchant Navy.
Very neat thanks for the idea.

Digger

[peterseager]

The spark arrester fitted to my Manor is exactly like that on John's Hunslet. Works fine but takes up a lot of space. The builder was obviously very careful about where he put the plumbing in the smokebox so may be a problem for a retro-fit. The upside is that its easy to clean the tubes!

Peter

[Smifffy]

The bits that burn holes in my chest and hair would certainly pass through 5mm mesh - all I want going through is the hot gases - still not implemented it but will report once I've got round to it.

I'm assuming DrJ that you get a lot of bits coming through your chimney looking at your photo ?
;D

Sorry, but someone had to say it!

[davidm]

On my Simplex I have a mesh tube that fits inside the peticoat pipe and rests on the top of the blast pipe. It's far from ideal theoretically (the blast cone is impeded) but seems to work reasonably well in practice while is is clean.

The lubricator is over generous so the mesh gets clogged after a couple of hours of running. The chimney is a easy push fit on the peticoat pipe so it can be removed, then the spark arrester can be replaced just by pulling it out.

I have attempted an improved design with a largers surface area and not impeding the blast cone, but fitting anything round the steam pipe and the blower pipe is not straightforward. It just goes to emphasise that the screen needs to be designed in to the smokebox from the word go!





David

[davidm]

Well... the more I looked at those pictures of my Simplex spark arrester the more I thought I had to do something better. So as a temporary measure I did this -



This is after an afternoon's running at a children's birthday party, round about 6 miles in all. The difference is remarkable. The fire draws better and the boiler steams much better, almost too well with the safety valves lifting more or less all round our track. I just hadn't realised how much the old arrangement was limiting steaming!

David

[fred55]

jgb's birdcage is the neatest fix, but looking inside my smokebox, I think that broziers flat screen could be the answer for me

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[fred55]

I haven't done the mod yet, but I did pick up this waste bin (I only paid $10) which will contains enough material for half a dozen locos, or several failed attempts ;D
The raw material is a bit scarce in the antipodes

www.officeworks.com.au/retail/products/Catering-and-Cleaning/Bins/Office-Bins/IT4341;jsessionid=(J2EE5996400)ID1326849750DB11197336246979379334End;saplb_*=(J2EE5996400)5996450

There is a cup sized penholder that fits neatly over the stack, as a temporary measure. Pete