Submarine Exposure Guidance Levels for Selected Hydrofluorocarbons: HFC-236fa, HFC-23,and HFC-404a (2000)
Chapter: 4 Hydrofluorocarbon-404a
4
Hydrofluorocarbon-404a
HYDROFLUOROCARBON (HFC)-404a is a gaseous mixture of three halocarbons—52% HFC-143a, 44% HFC-125, and 4% HFC-134a. It is used as a refrigerant in ice-cream machines. The U.S. Navy is considering installing a single ice-cream machine aboard each of its submarines. The Navy does not intend to perform servicing of this equipment when its submarines are under way, so the only HFC-404a aboard will be in the ice cream machine (i.e, there will be no cylinders of HFC-404a aboard). The refrigerant systems of the machines are sealed and operate in a manner similar to that of a household refrigerator.
To protect submariners from large accidental releases or low-level slow releases of HFC-404a, emergency exposure guidance levels (EEGLs) and continuous exposure guidance levels (CEGLs) are needed to avoid adverse health effects from short-term or prolonged exposures to HFC-404a and to avoid degradation in crew performance. No toxicity studies on HFC-404a were available, so the subcommittee reviewed the available data on its three components—HFC-143a, HFC-125, and HFC-134a. The subcommittee used these data to determine 1-hr and 24-hr EEGLs and 90-day CEGLs for each of the components, and then those values were used to calculate exposure guidance levels for HFC-404a on the basis of percent composition of the individual components. The calculated EEGLs and CEGL for HFC-404a were used to evaluate the Navy's proposed exposure guidance levels for HFC-404a.
