Hello Rogerio,
I've seen this static issue give big electric shocks (very uncomfortable) and discharges even to the point of melting the powder hose itself!
So far what has been helpful with this is to use a Nylon or PTFE Anti-static hose. As Bob said, this has carbon black as an additive to allow the tubing to disperse the static electricity. You can supplement this with a metal (steel or copper) braided sheath that goes over the outside of the powder hose. This sheath should be earthed at the powder feeder end of the line. Any metal transitions in the powder hose should also be earthed to allow any static to dissipate.
Sometimes the powder hopper in the feed system isn't correctly earthed either so this should be checked.
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Nicholas Curry
Consultant
Thermal Spray Innovations
Bruck an der Großglocknerstraße
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