You have to feed a gaseous reactant to a reactor at a constant rate of $1000 \mathrm{scfm}$. The gas is stored in a tank, at $80^{\circ} \mathrm{F}$ and $500 \mathrm{psig}$, that is located $20 \mathrm{ft}$ from the reactor, in which the pressure fluctuates between 10 and 20 psig. You know that if the flow is choked in the feed line to the reactor, then the flow rate will be independent of the pressure in the reactor, which is what you desire. If the feed line has a roughness of 0.0018 in., what should its diameter be in order to satisfy your requirement? The gas has a MW of 35 , an isentropic exponent of 1.35 , and a viscosity of $0.01 \mathrm{cP}$ at $80^{\circ} \mathrm{F}$.