Hallo All.

I've been playing with a 1/2" NARB recently, all was going well. Forge-welds Ahoy!

Yesterday, I shut the forge off for maybe 20-30 mins. When I came to restart it, the NARB block appeared to have taken on enough heat that the propane was igniting in the mixer tube/plenum, and after only a few mins, the plenum was glowing. Totally cool today, and started up with no issues.

I can understand why this happened, (I think, normally, the gas/air flow cools the block).

But, I ask for the collective knowledge;

• Is this a normal problem with Ribbon burners?
• Is this a design issue unique to my forge?

The burner is on the side of the forge, firing across the side wall, so also some chimney effect. the block and liner is made of 1600 c alumina refractory (As much as I tried, I couldn't source kast-o-lite)

 

Any help appreciated

 

 

Mine heat up to ignition temps in the plenum after a couple hours of steady use. If I'm taking some time to do something else say lunch, I aim an air hose down the burner and let it cool the block.

Be careful your compressor isn't spitting water or B A D things might happen to the block. Set the air hose nozzle back from the burner tube a ways and keep your compressor tank drained.

Frosty The Lucky.

so... Normal?

Thanks for the speedy reply Frosty - You're a treasure!

For home builds it is. We just happened to be sitting at our computers at the same time but thanks just the same. 

Frosty The Lucky.

The only "solution" I've found to this issue so far is a deep block with a lot of very small flame ports. 

My current burner has about 3" between the flame face and plenum and has around 180 holes of about 1/8" diameter, and I'm using a 3/4" mixing tube.  I couldn't get a great shot of it, but here it is shortly after firing up at very low pressure. I've been able to crank it up to welding heat then back down to barely running without any burn back into the plenum. I can light it back up after being shut down without a problem. It doesn't pop when I shut down the gas either. 

It's not perfect and I do get some flame lift at the bottom of the burner block at first (as you can see), but overall I'm happy with it.

Thanks Buzzkill. I've been following some of your posts on NARBS - super helpful  

My holes are quite large, and it's a very small forge, so there may well be room for improvement. 

I used crayons, about 5/16" and believe that's too large but can be tuned work well enough.

Frosty The Lucky.

Hi Simian,

My first NARB had fewer holes with bigger diameters, and the flame would burn back into the Plenum and burn there, producing a nice orangey glowy spot!!

The second one had many more holes with a smaller diameter, and spread apart more widely, and that has worked perfectly for me and my 3/4" AMAL propane injector ever since.  Here is a link to that thread that shows the two designs.  The second link is earlier on the same thread, that shows the glowing Plenum!  

 

 

This is what the Flame look like now.

 

Hope this helps.
Tink!

WOW, that sure brought back memories, Tink! That is one LONG thread with a lot of good designs and build techniques.

Frosty The Lucky.

Hiya Frosty,
I learnt a lot during that thread, and then added my own learning back into it, to help others.
I think its a great resource, and the one I'd always point people at, to learn about NARBs, etc.

Tink!

I've read most of that thread prior to building mine

So. my holes are about 8mm (5/16") and it will run from practically zero PSI all the way up to 30+. This is with a 1/2" Amal burner in a tiny forge (by design, about 130cu in). The Amal is epic, and can be adjusted from a rich to lean flame in seconds.

Pics or it didn't happen!

(it's only on the anvil for testing, and this is seconds after lighting)

And after about 10 mins - it really is that bright, it's not just the camera - Zircon coating.

 

It's whisper quiet, and uses tiny amounts of propane - I haven't even managed to get my bottle to frost up yet, which was a huge problem on my Devils Forge.

Looks like you nailed it!  The only suggestion I have is to build a support to secure the burner/mixing tube in place.

Why-O-why didn't you give me that advice earlier?   The weight of the block/burner cracked the casting on the first firing.

The whole thing was proof of concept, and I didn't expect it to work, so no real tragedy...

Hey back Tink! That has to be one of my favorite ever threads, we just kept feeding off each other, experimenting and reporting back. We advanced from a "Why not?" Notion, to I don't know how many different successful home built multi-orifice burners, around the world.

It was such a good time and it goes on! 

Frosty The Lucky.

 

 

Hiya Frosty,

It is one of my all-time favourite thread for just those reasons. It was a fun time, and still makes me grin.  While suggesting links to someone, I ended-up reading it all through again from about page 18 to 43 just for the fun of it.

My other favourite thread was AFB's 3d Printed Plastic Burner Experiments, as it was great to see the testing of ideas and the evolution of a great burner technology.
Ahh the good old days!!! 

Tink!

Oh, me too, the ribbon burner thread is a good read.

AFB's printed burners made me want a 3D printer. Briefly, they're too expensive for my limited wants. 

I love those moments when a brain storming session turns into a tornado and the ideas and expertise fly.

Sadly Covid and Glenn's passing have taken some of the old timers and spirit from the forum. Anymore seeing more than 5-6 posts in my "unread" folder excites me, then makes me a little sad.

Frosty The Lucky.

Bosh

 

Hmmm... fired it up at the weekend, and after about an hour it had burnt back into the plenum. Dang. 

Blocked two of the central holes and had a go today - seems to be runnning hotter, and managed an hour (at lower pressure than before)without any issues. Will try to give it a longer burn at teh weekend.