Valve stem packing

Under the Environmental Protection Agency's soon-to-be-promulgated permit regulations, all major sources of air emissions will be required to obtain new operating permits. The regulations affect any source with the potential to emit 10 tons annually of a single hazardous pollutant or 25 tons of all listed air toxicants. The states will be responsible for issuing these permits and must submit their programs, consistent with federal guidelines, by Nov. 15, 1993. The EPA has the authority to lower individual pollutant cutoff levels, several of which have been proposed. The 1990 Clean Air Act Amendments have mandated that: flanges and valve-stem emissions will be monitored; gasketed flange leakage concentrations for gas, vapor and light-liquid service will be limited to 500 ppm or less; maximum valve-stem seal leakage concentrations will be limited to 10,000 ppm for the first year of the new regulations and then be reduced to 500 ppm; for heavy liquids, an initial limit of 500 ppm will take effect. If these emissions exceed 10,000, or 500 ppm after their first year, corrective action must happen within five days. 4 figs.