Engineering Control Assessment Of The Plastics And Resin Industry. Case Study: Manufacture Of PVC By Bulk Polymerization.
NIOSH 1976:23 pages
A plastics industry and synthetic resin industry (SIC-2821, SIC- 2823, and SIC-2824) engaged in the manufacture of vinyl-chloride- monomer (75014) (VCM) were assessed for occupational hazards. VCM contamination and noise pollution were evaluated with reference to engineering controls designed to reduce the hazards. Bulk polymerization process (reaction and stripping) was performed within a totally enclosed environment and the process cycle was computer controlled, thus reducing the possibility of VCM escape due to human error. The system reduced the autoclave and heat reflux vapor condenser maintenance requirements. VCM recovery operations were designed to reduce the load on the compressors. The polymerizers and autoclaves were provided with dual rupture discs to minimize VCM loss to the atmosphere and the former was pressurized to atmospheric pressure with nitrogen to reduce potential exposure to employees. The vent stacks placed 80 feet above the process building prevented the reentry of VCM into the building. A system was set in place for rapid detection and prevention of leakage of VCM. The local exhaust ventilation system was controlled by the installation of permanent exhaust hoods or flexible hoses at 34 process points. General ventilation comprised of about 19 and 37 air changes per hour during winter and summer, respectively, with an emergency monitor alarm system set to detect above 900 parts per million (ppm) VCM. Monthly ongoing monitoring of VCM showed area samples to contain less than 1ppm. A reduction of worker exposure to respirable VCM was also seen, particularly between 1974 to 1975 following institution of engineering controls. Requirements for respiratory protection from VCM were integrated into the monitoring system and workers entering autoclaves for cleaning were required to wear a special suit, hood, and work gloves. Dust contents were kept below 15 milligrams per cubic meter and noise at 90 to 92 decibels. The author concludes that the engineering challenge for control of VCM to 1ppm during polymerization was met.
NIOSH-Author; Plastics-industry; Employee-exposure; Safety-research; Exposure-levels; Control-methods; Industrial-engineering; Toxic-vapors;
2821; 2823; 2824;
NIOSH, Robert A. Taft Laboratories, Cincinnati, Ohio, 23 pages