Worker Exposure Monitoring of Suspended Particles in a Thermal Spray Industry
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JTTEE5 16:214–219 DOI: 10.1007/s11666-007-9027-6 1059-9630/$19.00 Ó ASM International
Worker Exposure Monitoring of Suspended Particles in a Thermal Spray Industry Nikolaos Petsas, Giorgos Kouzilos, Giorgos Papapanos, Michalis Vardavoulias, and Angeliki Moutsatsou (Submitted May 12, 2006; in revised form December 26, 2006) The purpose of the present work was the investigation and characterization of the quality of air in a thermal spray industry, in Greece. The activities that take place in the specific facility, as well as in most other similar industries, include thermal spraying and several mechanical and metallurgical tasks that generate airborne particles, such as grit-blasting, cutting and grinding of metallic components. Since the main focus of this work was the workers exposure to airborne particles and heavy metals, portable air samplers with quartz fiber filters, were used daily for 8 h. Three samplers, carried from different employees, were used for a period of 1 month. Results showed that both particles and heavy metals concentrations were low, even in the production site, which was the most susceptible area. The only exceptions were observed in the case of cleaning and maintenance activities in the thermal spray booth and in the case of spraying outside the booth. The main reason for the low concentrations is the fact that most of the activities that could produce high-particle concentrations are conducted in closed, wellventilated systems. Statistical elaboration of results showed that particles are correlated with Ni, Cu, Co. The same conclusion is extracted for Fe, Mn. These correlations indicate possible common sources.
Keywords
heavy metals, monitoring, quality of air, suspended particles, thermal spray, workers exposure
1. Introduction Thermal spray is a generic term for a group of coating processes used to apply metallic or non-metallic coatings on various substrates and for several applications, such as wear and/or corrosion resistance, thermal insulation, and many others. These processes use the thermal energy generated by chemical (combustion) or electrical (plasma or arc) methods to heat the coating material (in powder, wire or rod form) to a molten or semi-molten state. The resultant heated particles are accelerated and propelled, by either process gases or atomization jets, toward a prepared surface. On the surface, the heated particles impact, flatten and solidify, thus forming thin layers or lamellae, which adhere to the substrate surface. Coating is built layer by layer and results from the relative movement of the ‘‘spraying gun’’ and the part to be coated. Spraying procedure takes place either manually (a trained sprayer moves the gun by hand) or, usually nowadays, automatically inside spray booths (Ref 1-3).
Nikolaos Petsas, Giorgos Kouzilos, and Angeliki Moutsatsou, Department of Chemical Engineering, Laboratory of Inorganic Analytical Chemistry, National Technical University of Athens, 9 Iroon Polytechniou Avenue, Athens, 15773, Greece; Nikolaos Petsas, Giorgos Papapanos, and
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