A typical liquid storage process is shown in the figure, qi and q are volumetric flow rates, assuming thatthe liquid density is constant and the tank is cylindrical with cross

sectional area A, and the tank has avalve at the outlet which has a flow head equation of \boldsymbol{q}=\frac{1}{\boldsymbol{R}_{\mathrm{r}}} \boldsymbol{h} Then the differential equation which describes this process will be A \frac{d h}{d t}=q_{i}-\frac{1}{R_{v}} h