Pulsed plasma jet paint removal

Abstract

Paint is removed from bridges and structures by directing pulsed plasma jets at coatings on surfaces. The repetitively pulsed plasma jets ablate the coatings, and the resulting products are removed by reduced pressure in an enclosure. Plasma jets in an array are moved along a surface, with the jets overlapping. Power is controlled to remove the topcoats and one or more layers of topcoat without damaging an underlying primer coat, or to remove a primer coat to the bare surface. Jets in the array overlap to completely remove the coating. The pulsed plasma jets impact the surfaces directly in front of the plasma jets, and the gases flow outward, carrying ablated materials away from the surfaces. The enclosures have openings near the coated surface for allowing the inflow of ambient air into the reduced pressure enclosure to prevent escape of ablated products from the enclosure. The use of inert gas working fluid reduces formation of undesirable byproducts. The application of pulsed plasma jets removes coatings, and paint in particular, with minimal waste and contaminants. The array is moved uniformly along the surface to effect complete removal without contaminating the environment, while minimizing hazardous waste disposal requirements.