Submarine Exposure Guidance Levels for Selected Hydrofluorocarbons: HFC-236fa, HFC-23,and HFC-404a (2000)
Chapter: 1 Introduction
1
Introduction
IN ACCORDANCE WITH the Montreal Protocol on Substances That Deplete the Ozone Layer, efforts are under way to replace the chlorofluorocarbons (CFCs) used in refrigeration units. One class of chemicals replacing the CFCs is the hydrofluorocarbons (HFCs). These chemicals do not contain chlorine and do not contribute to the destruction of the stratospheric ozone layer. Their use as replacements for the CFCs in refrigeration units is expected to expand.
The U.S. Navy proposes to use HFC-236fa and HFC-404a as refrigerants aboard its submarines; specifically, HFC-236fa is being considered for use in centrifugal chillers, and HFC-404a is being considered for use in ice-cream machines. Because of the closed environment of submarines, the Navy plans to set emergency exposure guidance levels (EEGLs) and continuous exposure guidance levels (CEGLs) to protect its personnel from potential adverse health effects, both short- and long-term, caused by inhalation of those chemicals as the result of accidental releases.
The Navy proposes to set a 1-hr EEGL of 2,000 parts per million (ppm), a 24-hr EEGL of 1,000 ppm, and a 90-day CEGL of 100 ppm for HFC-236fa and HFC-404a. The Navy also proposes to apply those guidance levels to HFC-23, a combustion product of HFC-236fa. These levels are the same as those established for chlorofluorocarbons CFC-12 and CFC-114.
