3. 3.49. The great Boston molasses flood occurred on January 15, 1919. In it, 2.

Question

3. 3.49. The great Boston molasses flood occurred on January 15, 1919. In it, 2.3 million gallons of crude molasses flowed from a 30-foot-high storage tank that ruptured, killing 21 people and injuring 150. The estimated specific gravity of crude molasses is 1.4. What were the mass of molasses in the tank in lb and the pressure at the bottom of the tank in lb,/in2? Give at least two possible causes of the tragedy FETY Small animals such as mice can live at reduced air pressures down to 20 kPa absolute (although not comfortably). In a test, a mercury manometer attached to a tank as shown in the figure below reads 64.5 cm Hg and the barometer reads 100 kPa. Will the mice survive? 4. 64.5 cm Hg

Explanation / Answer

Ans 3.49

Mass of molasses = density x volume

= specific gravity x density of water x volume

= 1.40 x 62.43 lbm/ft3 x 2.3 x 10^6 gallon x 1ft3/7.48052gallon

= 2.687 x 10^7 lbm

Pressure at bottom of the tank

P = Patm + density x g x h

= 14.7 lbf/in2 + (1.4 x 62.43 lbm/ft3) x (32.174 ft/s2) x (30 ft)

= 14.7 lbf/in2 + (84362.158 lbm/ft-s2) x (1lbf/32.174 lbm-ft/s2)

= 14.7 lbf/in2 + (2622.06 lbm/ft2) x (1ft2/144in2)

= 14.7 lbf/in2 + (18.21 lbm/in2)

= 32.91 psi

Pressure at the bottom was enough to crack at the bottom near manhole.

This high pressure was developed due to rise in temperature.

Designing of the tank was not upto the standard mark due to this 32.91 psi pressure has not been handled by the material of construction of the tank.

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