Abstract
The effect of spray-painting gun choice, high volume-low pressure (HVLP) or conventional, on solvent and particulate overspray concentrations was experimentally studied in a downdraft spray-painting booth. This experiment was conducted by repeatedly applying two coats of paint to a car body shell. The two spray-painting guns were a gravity-fed conventional and a gravity-fed HVLP gun. During each experimental run, particulate overspray concentrations, solvent vapor concentrations, film thickness on the autobody, and mass of paint were measured. The film thickness per mass of paint for the HVLP gun was 33% higher than that for the conventional spray-painting gun. This difference was statistically significant (p=0.0015). Apparently, the HVLP spray-painting gun had a much higher transfer efficiency than the conventional spray-painting gun. Also, the particulate overspray concentration per unit of film thickness for the conventional spray-painting gun was twice that of the HVLP gun. Again, this difference was statistically significant (p=0.0009). Finally, the HVLP spray-painting gun reduced the overall solvent vapor concentrations measured in the booth by 21%, which was not statistically significant. However, solvent vapor exposures measured on the worker were reduced by a factor of 2 when using the HVLP gun. This difference was statistically significant (p=0.02).