Dust Deputy query

Re: Dust Deputy query

Dick Coers

I assume a Dust Deputy is designed for a certain air flow range. No idea the size of your shop vacs, so very hard to even guess. Having trouble visualizing how a shop vac without a Dust Deputy moves coal. Do you run the vac till full, then dump it over? Hard to imagine how that beats using a 5 gallon bucket to carry the rice coal.

Re: Dust Deputy query

Tom Norton

I have a auxiliary hopper next to my boiler the 2 shop vavs are connected to it. Then a 2" PVC pipe runs across the basement ceiling,about 16', then I have a hose. Works great but need 2 vacs.

I had used the bucket system for a number of years but no matter how careful I was I always had just. This system bis working great. It was not my idea I got it from a coal burner forum.

Re: Dust Deputy query

Tom Norton

I also emailed Oneida and they just responded. I can use 2 vacs and they do not need to be identical.

Thanks for your help!

risk of Coal dust explosion ?

ian neuhaus

doesn't sound a very safe procedure to me.

The classic coal mine disaster is when a small scale methane explosion dislodges loose coal dust that then ignites, blowing the mine to bits.

At a guess...

John in NM

And it is just that, the danger is likely minimal due to the type of coal - anthracite. It is the hardest and most dense type of coal, and from what I read, the hardest to ignite and the least dusty.

I had exactly the same thought you did however, and I would probably be pretty careful about such a system, since vacuums move dust in air and that is the textbook means of generating static followed by a spark.

I bet if you substituted normal bituminous coal, you'd get a boom. I remember visiting a portland cement plant once, and the tour was fascinating - they cooked the various minerals to make the cement using air entrained coal dust - it burned like a gas, though I've long since forgotten the temperature (eg like acetylene or propane?). They must have done a lot of work to prevent sparking, even though all the ducting was stainless it is a huge risk - just like with pressurized gases.

sawdust is an explosive dust also

GolfSteve in Calgary

There are no answers below, just questions to ponder.

My first thought was to consider how dusty the coal is. Fine dust is more dangerous than coal lumps, and presumably the coal is washed and relatively coarse. You would also need to consider non-standard conditions, such as what happens when you are vacuuming the dregs left in the bottom of the hopper where the fine dust might accumulate even though the bulk of the coal is lumps, and the dust might also be drier due to sitting in the hopper for a long time.

My second thought is that wood dust is also an explosive dust, and would we consider this set-up to be hazardous for sawdust? Should we? Is coal dust more explosive than sawdust?

With the airflow that the system can deliver, is it possible to transport a concentration of coal dust that falls within the explosive concentration limits?

Can the vacuum motors generate sufficient energy (spark or surface temperature) to become an ignition source? Is the airflow/coal dust directly exposed to the motor windings or is there only indirect contact?

Are there layers of coal dust formed that might ignite/smoulder or contribute the sudden formation of dust clouds?

Water Separator  *LINK*

Dustmaker Mike

I use a water separator in my sandblasting cabinet when I use coal slag or sand. I made it out of a 5 gallon bucket with a lid and a few PVC couplings. Looks alot like this. It keeps the fine particulars in the bucket of water. It might work for this application.


Water Separator

Re: Dust Deputy query

Don Stephan

Could a meaningful reply be expected from the manufacturer of the boiler regarding explosive hazard?

Re: At a guess...

Bruce, a MN Galoot

Years ago, my office was right next to the state office of OSHA. A question arose about the level of dust in a grain elevator following an explosion. I asked the director what was considered to be a maximum level of dust considered to be safe.

His answer? No level of dust is safe. Any dust has potential for an explosion.

Re: At a guess...

Dick Coers

OSHA went on a terror for a while on residual dust sitting on top of piping, ceiling joists, etc. What they say happening was something would strike those items and this rain of really fine dust would slowly drop. It made for near perfect conditions to ignite. Dust flying through a dust pipe is not so easy. Most spark issues cause trouble in the collection bin of the dust collector. Get an ember in a pile of dust with high velocity air going over it, and you get a fire. Then blow a fine mist of sanding dust into the fire and boom. Anything is possible with dust though. We had a fire insurance assembly at our high school in 1968. The guy had this cast iron chamber with a spark plug in it. He blew in a small amount of dust and hit the switch. BOOM! Then he doubled the amount of dust and we held our breath. He hit the switch and nothing happened. Same as a engine, air/fuel ratio is critical for combustion.

but maybe not as explosive as some coal dusts

Ian Neuhaus

I found this https://pdfs.semanticscholar.org/c050/3cda4f235e9ab14fd92d196baa12be4fd985.pdf

inter alia it advises that

bitumous coal dusts are more explosive than anthracite coal dusts,

the as the dust particle size gets smaller the risk of an explosion increases,

that the ignition temperature of a coal dust layer decreases as the volatile content increases.

At high volatile contents, the ignition temperature of a coal dust layer approaches a limiting temperature as low as 160EC (320EF).

importantly, heat is more important than static electricity when it comes to initiating a coal dust explosion