General Motors Corporation
The painting operation uses purge thinner to clean paint gun tips, paint lines, and surface areas in the paint booths. Purge thinner cleaning effectiveness is critical to avoid craters, pits, and other anomolies in a paint job. Purge thinner formulation prior to May 1996 contained 50 percent xylene, a reportable VOC. GM successfully proposed and tested a new formulation containing only 2.8% xylene (which reduced the VOC content from 62% to 34.9%).
The new formulation uses part acetone substitution for xylene which lowers the flashpoint of the material, makes any waste more suitable for fuels blending, and reduces environmental risk in the event of any release.
Purge thinner use in 1995 was 184,366 gallons (for 185,126 trucks) while 1997 use was 137,793 gallons (for 160,167 trucks). Material usage of 0.996 gallons per vehicle in 1995 dropped to 0.860 gallons per vehicle in 1997. VOC emissions per vehicle dropped from 7.28 pounds per vehicle in 1995 to 2.07 pounds per vehicle in 1997.
Details of Reductions
Additional Information :
This material substitution decreased solvent-related quality defects from 32 to 1.5 per day. VOC emissions were reduced 5.21 lbs/vehicle, and material usage was reduced 25%. The new formulation costs $1.60 per gallon compared with $2.74 per gallon for the previous formulation.