Radius of Exposure (ROE) Calculation

Using the values of coefficients "A" and "B" in Table C-1, the radius of exposure (ROE) for various hydrogen sul­fide release rates (H₂S) can be mathematically predicted us­ing the following equation:

ROE - Antilog [A X log (H₂S) + B]

For a continuous release, enter the hydrogen sulfide re­lease rate (H₂S) in standard cubic feet per hour (SCFH). For a puff (instantaneous) release, enter the quantity of hydrogen sulfide (H₂S) released in standard cubic feet (SCF).

C.9 Sample Calculation—Continuous Release (Daylight)

Determine the ROE_{IOO ppm} for a continuous release of 100 percent hydrogen sulfide gas at a rate of 11,170 SCFH in daylight (PG D stability) conditions and 5 mph wind speed. Using Table C-1, the coefficients applicable to this scenario are: A - 0.58; В - 0.45. Using the equation in Par. C.8:

ROE_100ppm - Antilog [0.58 x log (11,170) + 0.45] - 628 feet.

C.10 Sample Calculation—Continuous Release (Nighttime)

Determine the ROE_)00p()in for a continuous release of 100 percent hydrogen sulfide gas at a rate of 11,170 SCFH in nighttime (PG F stability) conditions and 2.2 mph wind speed. Using Table C-1, the coefficients applicable to this scenario are: A - 0.66; В - 0.69. Using the equation in Par. C.8:

Antilog [0.66 x log (11,170) + 0.69] - 2,300 feet

 

C.11 Sample Calculation—

Instantaneous Release (Daylight)

Determine the ROE,,,^^ for an instantaneous release of 100 percent hydrogen sulfide gas of 1,117 SCF in daylight (Slade A stability) conditions and 5 mph wind speed. Using Table C-l, the coefficients applicable to this scenario are: A - 0.39; В - 1.91. Using the equation in Par. C.8:

ROE_100ppm - Antilog [0.39 x log (1,117) + 1.91] - 1,255 feet.

C.12 Sample Calculation—

Instantaneous Release (Nighttime)

Determine the ROE_l00p(m for an instantaneous release of 100 percent hydrogen sulfide gas of 1,117 SCF in nighttime (Slade В stability) conditions and 2.2 mph wind speed. From Table C-l, the coefficients applicable to this scenario are: A - 0.40; В - 2.40. Using the equation in Par. C.8:

. Antilog [0.40 x log (1,117) + 2.40] - 4,161 feet.

ROE

lOOppm'