[BProckets] Ceramic Media-volume/pound?

[f46 at comcast.net]

Dave,

I would be interested in purchasing some.
Could you offer an estimate of the cubic inches occupied by a given weight of the media? Not just the volume of the media itself, but also include the airspace between the individual pieces. IE, when you place a pound of media into a cylinder of 4" or 6" pvc pipe on end, and shake it a little, how high does the pile sit within the pipe, and what is the ID of the pipe you used to make the measurement?

Thanks.


> Hi Folks:
> 
> This post was inspired by a thread on the new Bprockets mailing list in
> which the correspondents expressed concern about the safety of using ceramic
> milling media.
> 
> As the author of "Amateur Rocket Motor Construction", and looking for a more
> effective milling media than the homemade brass pellets described in my
> book, about 5 years ago I did quite a bit of research on ceramic media, and
> based on talks with one of the manufacturers of the 90% alumina media
> (Coors), I ordered a sample of their 1/2" dia. 90% alumina pellets.
> 
> Concerned about sparking, I took 2 of the brand new pellets into a closet
> and closed the door. Then, holding one pellet in each hand, I struck them
> together as violently as I could. To my disappointment, the impact generated
> a faint, purple colored spark. When I asked the Coors tech support expert
> about this spark, he assured me that it was NOT an electrical spark, but a
> photon.
> 
> In a conversation that lasted about half an hour he explained that, when
> THEY first saw this "spark", they were VERY surprised and concerned. They
> make these pellets in sizes up to several inches in diameter, and they sell
> tons and tons of them to the grain-milling industry. The slightest chance of
> a spark causing a grain mill explosion would render the entire product line
> unuseable, so they sent a sample to a physics lab where they were subjected
> to EXTENSIVE testing.
> 
> The lab determined that the observed "spark" was indeed NOT an electrical
> spark, but a photon of an energy WAY below the threshold needed to ignite
> even a high energy chemical mixture. In the years since, Coors has continued
> to sell them not only to the grain industry, but to people who use them in
> other applications as well. I've also spoken with a person in the fireworks
> industry who uses them for milling high energy fireworks compositions, and
> he's never had an explosion.
> 
> On my own, I made an additional discovery that further allayed my fears
> about sparking. In my OWN experiments, I could only generate the photon
> effect with BRAND NEW pellets. After a few minutes of handling, just the oil
> from my fingers was enough to keep the effect from occuring. And I also
> found that a single mill run with charcoal or black powder (both contain
> residual organics) would contaminate the pellets enough to prevent the
> effect. To clarify, try as I might, I found it IMPOSSIBLE to create the
> photon with pellets that had been used for a single mill run, or even
> handled and subjected to the oil from my fingers. Since then I've milled
> several dozen batches of black powder with these pellets, and I've been VERY
> happy with the results. These Coors pellets are NOT perfect spheres. Each
> pellet is actually a short, squat cylinder with hemispherical ends, a shape
> that the Coors engineers determined was most effective for grinding things
> to a powder.
> 
> By doing my own microscopic particle size analysis, I've found that, when
> substituted pound-for-pound for the homemade brass pellets, these 1/2" Coors
> pellets mill my chemicals and the Teleflite propellants about 40% faster
> than the homemade pellets. Therefore I've decided to sell these pellets over
> the Teleflite website, but as of this date, September 23rd, 2004, the
> website is still under construction.
> 
> THEREFORE, IF THERE'S ENOUGH INTEREST, I COULD START SELLING THEM
> IMMEDIATELY ON EBAY. I have about 500 lbs. of the 1/2" Coors pellets in my
> storeroom, but I need YOU people to suggest what package sizes I should sell
> (i.e. 1 lb., 5 lbs., 10 lbs., etc.). Of course I want to keep my prices fair
> and competitive, so if someone is already selling the 90% alumina media, a
> link to their website and price pages would be appreciated. Awaiting your
> replies,
> 
> David Sleeter/Teleflite
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
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