Fire in dust extraction today!

[RobinBHM]

One of our machinists burst into the office just before lunch today shouting 'FIRE'......

I went running out and sure enough one of the 4 bag dust extractors had a fire.

Inside one of the bags, which was half full of dust there were flames. We quickly unclipped the bag and pulled it away and tamped the flames out then took the bag outside.

I then took off the other 3 dust bags which also had a bit of smouldering going on.

We started to tidy up and then realised smoke was coming out of the machine ports. It seemed quite bad at the panel saw so I went over to the machine and went to take off the flexi hose as I did so I put my hand on the 6" metal duct it was connected to.........bad idea, the pipe was so hot It burnt my hand! We then shut the blast gate and blew a carbon dioxide extinguisher up the pipe which did put it out.

We stripped down the 4 bag extractor and discovered smouldering embers were still burning inside the casing and 3 of the socks had burn holes still smouldering slowly.

Ive been in 2 minds this afternoon whether to strip down all the ductwork, but its about 20 metres worth mostly over 3 metres up so Ive been checking it and have seen no smoke anywhere so hopefully all is ok....... (I keep wondering if I should be going back tonight to check).


I rang P&J to see if they have any sock filters. 4 weeks delivery! Luckily I managed to get some ordered from ducting on line for delivery tomorrow. The extractor is hooked up to 6 machines so needs to be working soon.

 

[Woodmonkey]

Scary! Any idea how it started?

 

[NazNomad]

You can get a very flexible chimney sweeping rod with a flue brush on the end. Give the ducting a good clean out.

Was something sparking to cause the ignition in the first place?

 

[Vann]

... (I keep wondering if I should be going back tonight to check)...

Yup, I'd be wondering that and probably couldn't sleep.

Cheers, Vann.

 

[RobinBHM]

The panel saw had only been on for a few minutes a bit earler to straighten 3 boards, but it must have happened then I guess. Once before a piece of wood had got stuck in the panel saw, rubbing on the blade and then dropped down and started smouldering. I can only assume the same thing happened today and an ember got sucked into the ducting where it stopped at a bend where some bits had got lodged. After a while I suppose the extractor sucked up some embers which ended up in the dust bags and socks.

 

[Peter Sefton]

Scary!

I fitted a new bandsaw blade last week and it sparked for the first minute or two, possibly a weld spot hadn't been ground off. We took the dust bag and removed it from the workshop, these things do have a tendency to smoulder into the night :!:

Thanks for sharing, cheers Peter

 

[Adam9453]

Wow I bet that got your heart pacing!!
I was cutting some chipboard the other day and noticed some sheared metal in the edge which is obviously part of the board but a bit concerning given how little it can take to ignite dust.
Have you checked the material you were cutting for traces of metal in the cuts?
As the others have said I'd give it a good clean out with chimney brushes, empty all the bags etc and then run it for a bit with no other machines going so you can see if there's any further issues to be resolved.
Glad it wasn't more serious, good thing your guys are on the ball.

 

[woodpig]

I fitted a new bandsaw blade last week and it sparked for the first minute or two, possibly a weld spot hadn't been ground off.

Bandsaws that have the top or bottom thrust bearing the wrong way round (sadly by design) will readily spark. Not surprising really as by necessity both the blade and the bearing are made from hard metal.

 

[ColeyS1]

Savage,good job you caught it in time ! I went round the shop the other day servicing all the machines, pretty scary what I found. Two out of the 25 socks were clogged on the extractor.I had to drill out rivets just to get the panel off to have a look. I'll be having another look tomorrow to see if I can speed up access incase of a fire.Thanks for the heads up.
Glad it wasn't more serious, wouldn't hurt to have another look tonight for peace of mind.

Coley

 

[Peter Sefton]

I fitted a new bandsaw blade last week and it sparked for the first minute or two, possibly a weld spot hadn't been ground off.

Bandsaws that have the top or bottom thrust bearing the wrong way round (sadly by design) will readily spark. Not surprising really as by necessity both the blade and the bearing are made from hard metal.

I would say we only see a sparking bandsaw blade every 2 or 3 years, don't want to see anymore

Cheers Peter

 

[Togalosh]

That reminds me of the time I accidentally destroyed the massive external dust collector at my 1st job after leaving school. I scorched a door in a sander. Someone had put 220 grit belts in a big drum sander that ALWAYS has 50 or 80 grit in. I then attempted & instantly failed to take 5mm off a solid core door. None of the senior workers told me off or worried about it even though there was a fair bit of smoke coming out of the unhappy machine.

It was quite a while later that the commotion started.. I can remember watching the bosses son doing a very poor impression of Red Adair on a fork lift. Good job we have an amazing fire brigade.. & that it was outside.

I must get another fire extinguisher.

 

[jimmy_s]

maybe worth fitting these?

http://www.nordfabducting.co.uk/downloa ... -brochure/

 

[RobinBHM]

For peace of mind I popped back to check........seems ok

A close call today, probably less than 5 minutes more and the fire would more than likely have been too extensive to deal with.

It was certainly scary dealing with flames and glowing embers in dust extraction bags with wood dust in. Of course taking the extraction bags off in a hurry meant disturbing all the fine dust clinging to the inside of the sock filters.

I shall look into those spark arresters.

 

[ColeyS1]

Thank fuc for that !
I'd be interested to hear your thoughts on those spark arrestors. I'd never considered the real possibility of it going up in smoke so quickly. Having something always keeping an eye on things would certainly be helpful.
Cheers
Coley



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[RogerS]

Surely a spark arrestor is only going to prevent airborne dust exploding and not, as in this case, lumps of red hot metal coming off of a machine ?

Years back went to a meeting at Sony's new HQ. Still very much a building site. Shown up to the board room to wait for our host. The first meeting held there, as it turned out. We sat and waited. After a while I said 'Can anyone else smell burning?'. 'Yes' was the reply. So we looked into cupboards etc but couldn't see anything smouldering. "Must be coming in from outside from one of the builders fires", I suggested.
We carried on waiting. "That smell is getting stronger, isn't it" said my colleague. "Mmm...yes, I think you're right" I replied leaning back in the chair and gazing at the ceiling. To see symmetrical round very brown holes starting to appear in the ceiling tiles. The numpties had forgotten to cut the holes for the halogen downlighters. We tuned the lights off and exited the room. "I'd call the Fire Brigade, if I were you" I said, pressing the fire alarm button.

 

[Mr T]

A salutary reminder to check our systems. I remember when the extractor at Leeds Colleg of Art went up. The flames were impressive. Fortunately the extractor was sited outside, meant the college didn't burn down but also that it wasn't noticed until it was well alight.

Chris

 

[mbartlett99]

This is not directly on point but I think sufficiently close; several ships have gone to the bottom through laundry ducting fires. Lint builds up on filters and ducting (especially the corrugated pvc type) and then all it takes is an ember from the dryer to light it up. Can be difficult to deal with especially as the ducting is usually buried in cabinetwork and crosses decks.

As a result we inspect annually (with a borescope) or just get the duct cleaning guys in as a matter of course. Generally ductwork on ships now has to be steel (smooth sided). Galley ductwork has to be protected by its own fire suppression system and all have to have fire flaps.

Quickest way to clean it is to get a petrol leaf blower (not electric - not enough grunt) and blow the hell out of it.

Guess this only applies to larger installations so just food for thought if you're planning a new install.