Testing and Evaluation of Potential Hazards from a Teflon Impregnated Packing.

A Teflon impregnated, asbestos yarn packing material is being considered for use in submarines main feed and other water pumps. The Naval Research Laboratory was tasked to evaluate the potential hazard under the most severe conditions as well as more typical operating conditions. Under normal operating conditions, no significant amounts of hydrocarbons, fluorides, perfluorocarbons, and asbestos were discharged into the atmosphere or the lubricating, water stream. A trace amount of fluoride ion detected in the water samples can be attributed to a polyfluorinated surfactant identified during the g.c. - mass spectroscopic analysis. Under severe or dry operating conditions, some hydrocarbons, HF, fluorocarbons, and asbestos are discharged into the atmosphere. The observed hydrocarbons are easily absorbed by the charcoal filters, readily oxidized to CO2H2O by the catalytic burners, and should be essentially removed from the machinery space in 30 minutes with normal air exchange. However, the hydrocarbon concentration may reach 400 ppm in the vicinity of the pump, and the hydrocarbons have a characteristic unpleasant odor. The concentration of asbestos, HF, perfluorocyclopropane, and perfluoroethylene released under the conditions of the test and expanded into the machinery space of SSN 688 are below the currently established NIOSH standards. The most toxic decomposition product of Teflon, perfluoroisobutylene, can be produced in dangerous quantities only with simultaneous failure of the water lubricating system, the air handling system and with manual tightening of the packing. The likelihood of the triple failure occurring was assessed to be negligible.