Spark arrester design

This forum is dedicated to the Live Steam Hobbyist Community.

Moderators: Harold_V, WJH, cbrew

Glenn Brooks
Posts: 1294
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Spark arrester design

Post by Glenn Brooks » Fri Jul 13, 2018 11:15 am

Hello all,

Fire season is upon us here in the Northwest. Almost 1000 wildland fires in Washington and Oregon since January.

I’d like to find a way to operate my coal-fired Ottaway this summer, if possible.

Anybody have suggestions or a design for a spark arrester that I could fit to a smokestack?

Thanks much,
Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

User avatar
Marty_Knox
Posts: 1307
Joined: Thu Jan 09, 2003 6:50 pm
Location: Michigan, USA

Re: Spark arrester design

Post by Marty_Knox » Fri Jul 13, 2018 11:48 am

On my 2.5" scale 4-6-0 - stainless steel mesh.
IMG_1527.JPG
IMG_1528.JPG

rkcarguy
Posts: 701
Joined: Tue Aug 22, 2017 10:33 am

Re: Spark arrester design

Post by rkcarguy » Fri Jul 13, 2018 2:49 pm

Glenn,
Yes you'll need an SS mesh, something with a fine enough screen to not let embers pass through, but course enough wire that it doesn't burn up in short order.

Glenn Brooks
Posts: 1294
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Spark arrester design

Post by Glenn Brooks » Fri Jul 13, 2018 7:10 pm

Marty, what mesh size are you using? Does your design inhibit draft to much?

Thanks
Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

User avatar
Marty_Knox
Posts: 1307
Joined: Thu Jan 09, 2003 6:50 pm
Location: Michigan, USA

Re: Spark arrester design

Post by Marty_Knox » Sat Jul 14, 2018 7:35 pm

Glenn, I don't remember what mesh size it is. I bought the material at least 4 years ago. This is the second spark arrestor I've made from a square foot of material. I think it was 4 x 4 mesh. I do know I made the net area through the openings 1 1/2 times the area of the stack. It doesn't seem to restrict the exhaust.

Glenn Brooks
Posts: 1294
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Spark arrester design

Post by Glenn Brooks » Sat Jul 14, 2018 8:08 pm

Thanks Marty, the only thing I was able to find locally is some bronze “hardware cloth”. Maybe 1/8” mesh size. Hardware store also had some 1/4” galvanized screen, but it didn’t look durable enuf. And way to large to capture embers. The cloth is Probably to fine a mesh size, but at least it’s a starting point. I’ll give it a try, using your dimensions.

Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

User avatar
Fender
Posts: 2489
Joined: Wed May 02, 2007 8:33 pm
Location: Chattanooga TN

Re: Spark arrester design

Post by Fender » Sat Jul 14, 2018 8:35 pm

I think I used 6 X 6 mesh size stainless wire cloth from McMaster. It has openings that are about 1/8” wide. Seems pretty effective. But then, I live in the Southeast!
Dan Watson

User avatar
johnpenn74
Posts: 334
Joined: Tue May 04, 2010 12:54 pm
Location: Waiting for next assignment!

Re: Spark arrester design

Post by johnpenn74 » Sun Jul 15, 2018 8:13 pm

Do these things really work? Last time I was running at night I saw a lot of spark going up through the stack and cinder trap... which makes me ask how effective they are. Here the one on my engine.

The Costagon cabbage stack traps cylinder by deflecting the flow of air, which I would think is a more effective means to trap sparks than screening through a screen filter. This makes me wonder, is the functional component inside the stack screen track that is being missed here?

JP
Attachments
0828161326a.jpg
0828161327.jpg
0828161327a.jpg
0828161327b.jpg
CAM02838.jpg
John Pennington

Project
2 Mich-Cal Shays
Allen 4-4-0 Narrow Gauge Conversion
Reading A5a Camelback 0-4-0
USRA 0-6-0
Clishay
4 Western Wheeled Scraper NG Dump Cars
N&W 4-8-2
ICM 2-10-2
4 Modern Stake Cars
L&N Caboose
4 Big Four Conversion Gondolas

Like I'm actually gonna build all this stuff :-P

User avatar
Fender
Posts: 2489
Joined: Wed May 02, 2007 8:33 pm
Location: Chattanooga TN

Re: Spark arrester design

Post by Fender » Sun Jul 15, 2018 8:26 pm

A screen will not stop 100% of the sparks. But it will catch the bigger ones that are most likely to reach the ground and start a fire. A centrifugal arrestor such a Radley & Hunter stack or a Baldwin Rushton stack is designed to swirl the sparks around internally, until they disintegrate into smaller pieces and burn up.
The larger cinders, having more mass, are trapped while swirling along the inside surface of the stack, while the smaller ones (with lower mass) are ejected out of the stack or drop down into the hopper, to be dumped out later.
Dan Watson

Glenn Brooks
Posts: 1294
Joined: Mon Nov 10, 2014 1:39 pm
Location: Woodinville, Washington

Re: Spark arrester design

Post by Glenn Brooks » Sun Jul 15, 2018 9:00 pm

On an earlier thread a couple of people who have operated these conical shaped stacks on full sized locomotives said they did not work, as the shape and various apparatus inside the stack kills draft. Some do indeed capture sparks, but renders the boiler more or less useless. Another sidelight I remember from long ago is this style was reportedly developed early to mid 1800’s for wood burning locos, which produced a greater shower of embers from the burning wood than coal. Of all the patents issued for these stack designs, none seem to have prospered in actual use.

Marty Knox and a couple of local guys at the hardware store indeed have said hardware cloth will capture sparks, but tends to clog up very quickly due to the oily nature of coal smoke. So needs frequent cleaning.

I plan to experiment next week, and intend to graduate to slightly larger mesh size if necessary, hoping not to burn down the east side of the county during my engine trials. :shock:

Glenn
Moderator - Grand Scale Forum

Motive power : 1902 A.S.Campbell 4-4-0 American - 12 5/8" gauge, 1955 Ottaway 4-4-0 American 12" gauge

Ahaha, Retirement: the good life - drifting endlessly on a Sea of projects....

rkcarguy
Posts: 701
Joined: Tue Aug 22, 2017 10:33 am

Re: Spark arrester design

Post by rkcarguy » Sun Jul 15, 2018 10:29 pm

Glenn, there is a place on the valley highway in Auburn called McNichols, they make all kinds of mesh. Yes I'll admit I have zero live steam experience, but in my industry we have built them for anything from generators of many sizes to stack flares for refineries and power plants. The later have gone to more exotic catalytic type materials now so we don't do much of that work anymore though. I've also dealt with many of them in my dirt bike and car racing days as many of the events ran in Eastern Washington and Oregon required spark arrestors. It was a bummer to get one with galvanized or steel mesh as it burned out quickly. I remember this because my Dad roasted one, and got DQ'd when the checkpoint workers "test stick" went unhindered up the exhaust pipe. The rotary engine in the race car ran horribly hot and burned up everything, optimum exhaust temp was just under 1700*. I never came up with anything that would last, just had to fabricate these rings that would bolt in with the mesh in them and replace it every 2-3 events.
McNichols lists the % opening on the product, so you can get a fairly tight large wire mesh, and then size it such that you have enough open area that it won't restrict your stack. The link below would be a good product, course enough wire that it should last a while, and a small enough opening that should stop most of the sparks. Being this is a from a roll, you should be able to buy a sample or small piece pretty reasonably.
Heat flow through a tube or stack tends to focus the heat in the center, so some sort of diffuser that puts a *little* twist on flow could even out the heat and help the mesh last without inhibiting flow.
You are correct that the conical shaped stacks/tips/arrestors do not flow as well. There was one offered for motorcycles with a propeller type thing inside it, a tube of mesh and packing, and then a cone of mesh inside the exit end to stop the sparks. I wasted my money on it my 2-stroke didn't like it. Because the 4-stroke motors seem to like some back pressure, I was able to sell it to a friend and at least got some of my money back.

https://www.mcnichols.com/wire-mesh/squ ... -ss-380647

User avatar
NP317
Posts: 1287
Joined: Tue Jun 24, 2014 2:57 pm
Location: Northern Oregon

Re: Spark arrester design

Post by NP317 » Sun Jul 15, 2018 11:32 pm

When we rebuilt the 90-ton Climax Hillcrest Lumber #10 in 1982, The Boss insisted we install the Radley and Hunter stack on the new smokebox.
It was TERRIBLE, causing big steaming problems due to the poor drafting. We could not produce sufficient steam to get the light locomotive up the grades.
And thick black smoke just swirled up like a wimpy tornado. We had TOLD The Boss this would be the case, but noooo. He had to have that R&H stack.
As soon as his back was turned we installed the shotgun stack that also came with the locomotive.
Then we could make steam!
I understand that in later years Jack Anderson removed the center turbulator device from that R&H stack, and installed it just for looks.
Smart Guy.
~RN

Post Reply