Tribo-corona powder application gun

A gun for spraying a powder onto a work piece to form a coating, said gun comprising:

• a pistol-grip housing including a trigger actuated air valve coupled to a source of pressurized air and supporting a power supply that is operatively interconnected between said pressure activated switch and an adjustable potentiometer wherein said pressure activated switch is operatively interconnected to and activated by said source of pressurized air and said adjustable potentiometer is interconnected to a voltage indicator having a display positioned on an outer surface of said pistol-grip housing;
• a powder container disposed in fluid communication with said trigger actuated air valve wherein said powder is fluidized by air from said source of pressurized air when said valve is actuated;
• a nozzle having a first end through which said fluidized powder is introduced into a central passageway and a second end through which said fluidized powder emerges, said central passageway having at least one charging surface therein made of a first electrically insulated material suitable for electrically charging said powder by friction;
• a discrete tube disposed within said central passageway, separate from said central passageway, said tube having at least one charging surface thereon made of a second electrically insulated material suitable for electrically charging said powder by friction;
• and,
• a corona discharge assembly including an emitter rod positioned in substantially coaxial relation to said central passageway, a power supply positioned within said pistol-grip housing, a pressure activated switch operatively interconnected between said power supply and said trigger actuated air valve, a variable potentiometer positioned in said housing, and said emitter rod.