$2-20$ A cylindrical tank with a diameter of $15m$ is used to store $1600m^3$ of liquid benzene. To provide adequate protection during an external fire, determine the venting rate and the vent area if the maximum tank pressure is to be maintained at $250Pa$ gauge. Is the calculated vent area realistic, or should the tank specifications call for a weak$-$seam roof? Heat transfer to the tank is by radiation from the hot soot particles and gases in the flame and convection from the hot gases. The radiant flux emitted from many burning hydrocarbon fuels is approximately $95k\frac{W}{m^2}.$ This average accounts for fluctuations in temperature, emissivity, composition, and other variables in the flame. Note that the tank when heated from the fire will reradiate some of the energy it receives from the fire.