4. DATA: Temp = 30^oC; Tot Press = 1 atm. For xylenes Sat Vap Press = 11 mm Hg @ 30^oC; MWt = 106; Specific Gravity = 0.864. Assume k (non-ideal mixing factor) = 0.1

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Use the following information for problems 4, 5 and 6: A certain car gasoline tank holds 12 gallons of gasoline and takes about 3 minutes to fill. The molecular weight of gasoline is about 94 (gasoline is a mixture of several aromatic and aliphatic organic compounds), its vapor pressure at 77^oF (assumed ambient temp for these 3 problems; also = 25^oC) is 4.6 psi (31,700 Pa), and its liquid specific gravity is 0.7. Gasoline vapor under the ambient conditions prevalent during filling of a gas tank can be assumed to be an ideal gas. Assume ventilation is average with Q_v of 3000 ft³/min and k = 0.1 (non-ideal mixing factor). Assume atmospheric pressure = 1 atm = 14.7 psia = 101.325 kPa for all 3 problems.

5. (25 points) Estimate the concentration of gasoline vapor in the air around the tank, in ppm, as a result of this filling operation. Compare your answer to the TLV for gasoline. (Use equation 3-24 with the assumption that KA<< r_f V_c , and = 1 for splash-filling.) Ans: 552 ppm

6. (25 points) The tank is empty. (Empty is in quotes because an empty gas tank is actually full of gasoline vapors at the saturation vapor pressure, in this case 4.6 psi at 77^oF and 1 atm.) Many gasoline filling stations have scavenger systems to recover the gasoline vapors that are ejected from the tank as it is filled with liquid. You have probably seen these corrugated rubber recovery systems for vapor, which are installed as part of the filler hose. Estimate how many gallons of gasoline are recovered free to the station owner with each complete fill-up of the car under analysis, and for each 10,000 gallons of liquid gasoline dispensed.

Ans: 0.024 gal/tank; 17.1 gal/10000gal filled

6. (20 points) While filling the gas tank you accidentally spill some gasoline on the ground. It forms a pool 0.6 m (~2 ft) in diameter. You try to contain the spill while maintaining the same ventilation rate of 85 m³/min (3000 ft³/min). Estimate the concentration (ppm) of gasoline in the air in vicinity of the spill (a) if complete mixing is assumed ; (b) if the non-ideal mixing factor is 0.1. In each case compare the concentration to the TLV value for gasoline.

Ans: C = 300 ppm for complete mixing.