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  Electrostatic troubles with powder

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Author Topic:   Electrostatic troubles with powder
goulmik
Senior Member

Posts: 10
From:poissy
Registered: May 2003

posted May 23, 2003 04:53 AM     Click Here to See the Profile for goulmik   Click Here to Email goulmik     Edit/Delete Message   Reply w/Quote
Hi everyone,

we feed our extruder with a powder and a liquid.
The trouble is that the powder accumulates itself in the hopper... we've tried to connect it (the hopper) on the ground to prevent electrostatic loads.
The result was not very good; the powder still accumulates but in a more homogeneous way.
All suggestions are welcome!

thanks in advance
sincerely
Goulmik

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zabielski
Senior Member

Posts: 154
From:McHenry, IL USA
Registered: Nov 2002

posted May 23, 2003 06:58 AM     Click Here to See the Profile for zabielski   Click Here to Email zabielski     Edit/Delete Message   Reply w/Quote
goulnik:
The electrical "ground" must first of all be dedicated (seperate from the machine ground), and about 12 feet deep minimally (~ 4 meters).

A mild wayto keep the powder from accumulating is to introduce short shots of a sharp blast of air into the hopper intermittantly. I've done this for PP flake recyling and it works well.

You can do this with an expensive Programable Locic Controller, or just a cheap cam switch. I prefer a PLC, as you can then fine tune the on-off sequence, based on your output rate.

Can you indicate what generic family of poymer your using? I can only guess that it is non-polar.

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Tom C
Moderator

Posts: 141
From:Wharton, NJ, USA
Registered: Jun 2001

posted May 23, 2003 08:29 AM     Click Here to See the Profile for Tom C   Click Here to Email Tom C     Edit/Delete Message   Reply w/Quote
I have found that hanging chain or wire rope directly into the material in the hopper at several locations and connecting them to ground helps.

*** If the material develops static charge you should have it evaluated for dust explosion potential. ***

Tom C

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