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HYDROFLUOROCARBON-404A 74 TABLE 4-5 Submarine Exposure Guidance Levels for HFC-404a Components Calculated Guidance Levels Exposure ppm mg/m3* HFC-143a (molecular weight: 84.04) 1-hr EEGL 25,000 85,930 24-hr EEGL 4,000 13,749 90-d CEGL 700 2,406 HFC-125 (molecular weight: 120.0) 1-hr EEGL 7,500 36,810 24-hr EEGL 5,000 24,540 90-day CEGL 900 4,417 HFC-134a (molecular weight: 102.03) 1-hr EEGL 8,000 33,384 24-hr EEGL 5,000 20,865 90-d CEGL 900 3,756 aThese values were calculated using the following formula: where the value of 24.45 is the molar volume of air in liters at a pressure of 760 mm Hg and a temperature of 25°C. The 1-hr EEGL, 24-hr EEGL, and 90-day CEGL for HFC-404a were calculated to be 12,900 ppm, 4,300 ppm, and 800 ppm, respectively. The Navy proposes to use lower guidance levels of 2,000 ppm for the 1-hr EEGL, 1,000 ppm for the 24-hr EEGL, and 100 ppm for the 90-day CEGL, which the subcommittee concludes are conservative values that are protective of submariner health. CALCULATIONS Calculations Used to Determine EEGLs and CEGL for HFC-404a HFC-404a contains by weight: 52% HFC-143a, 44% HFC-125, and 4% HFC-134a The equation below was used to calculate the 1-hr and 24-hr EEGLs and 90-
HYDROFLUOROCARBON-404A 75 day CEGL for the mixture HFC-404a; f is the fraction of each component of the mixture and EGL is the component's corresponding exposure guidance level (which must be expressed in terms of milligrams per cubic meter): Using the values in Table 4-5, the EGLs for HFC-404a were calculated as follows: 1-hr EEGL: Of the mixture, 52% or 52,075 mg/m3 Ã 0.52 = 27,079 mg/m3 is HFC-143a 44% or 52,075 mg/m3 Ã 0.44 = 22,913 mg/m3 is HFC-125 4% or 52,075 mg/m3 Ã 0.04 = 2,083 mg/m3 is HFC-134a. These values can be converted to parts per million as follows: HFC-143a: 27,079 mg/m3 Ã 0.29 = 7,853 ppm HFC-125: 22,913 mg/m3 Ã 0.20 = 4,583 ppm HFC-134a: 2,083 mg/m3 Ã 0.24 =500 ppm. The 1-hr EEGL of HFC-404a = 7,853 + 4,583 + 500 â 12,900 ppm. 24-hr EEGL: Of the mixture, 52% or 17,341 mg/m3 Ã 0.52 = 9,017 mg/m3 is HFC-143a 44% or 17,341 mg/m3 Ã 0.44 = 7,630 mg/m3 is HFC-125 4% or 17,341 mg/m3 Ã 0.04 = 694 mg/m3 is HFC-134a.
