Metal dust

[ozzie34231]

My belt sander says, "Do not use vacuum if sanding metal".
Is there a real danger of explosion when collecting metal dust, or is this theoretical garbage?
I'm sanding aluminum most of the time.
Jerry

[Ken_Shea]

Jerry,
Does it warn of explosion ??

My guess is not that it would be explosive but that it would draw the abrasive dust up and into areas causing excessive wear.

Ken

[bbj]

well mixing metals could be disastrous. Steel dust will eventually rust and if you happen to have aluminum powder in there aswell, then you have a potentially lethal mix. A sufficiently hot heatsrouce will ignite it and it burns hot enough to almost instantly melt steel . I forget what that mixture is called now......

John

[Geof]

The name bbj cannot remember is Thermite; the reaction between powdered aluminum and iron oxide that can generate temperatures of up 3500 C., certainly enough to melt steel.

It is a small but real risk.

[ozzie34231]

Thanks All,
I just re-read the label.
It says to prevent a possible fire hazard do not use this when sanding metal.
Jerry

[John3]

Originally Posted by Geof The name bbj cannot remember is Thermite; the reaction between powdered aluminum and iron oxide that can generate temperatures of up 3500 C., certainly enough to melt steel. It is a small but real risk.

Powdered anything, especially powdered aluminum, powdered steel or worse yet a combination (thermite) is very explosive. Last year when things were a little slow at our shop. We emptied the dust collector and threw a pound or two of dust in a fire. The explosion was truly frightening.

After that I ditched two brush motor shop vacs because the guys would use them to pickup aluminum and steel dust.

Check out these links:

http://www.firemarshals.org/docs/Hay...n_and_Fire.pdf

http://www.youtube.com/watch?v=pIqC610k1gY

http://www.sparkdetection.com/proble...explosions.htm

Because of the explosion possibility, OSHA requires any dust collectors be statically grounded and place out side of buildings if they contain aluminum dusts.

John

[Geof]

Re: Not That Small Of A Risk

Yes I should have made it clear that I was talking in the context of a small belt sander with something happening spontaneously under normal usage.

Thermite itself, that is the iron oxide aluminum powder mix, burns very fast but it is not explosive. However, as you demonstrated the fine powder thrown into a flame burns so fast it is pretty close to an explosion.

Probably everyone in North America has seen the thermite reaction in operation; that is what occurs in the Space Shuttle solid boosters.

[Ken_Shea]

It seems the greatest risk for fire would be to have used the sander on wood and the dust being vacuumed into a container, then used on metal where sparks would surely occur and them sent off into the wood dust.