In order to pump a fluid of $\mathrm{SG}=0.9$ at a rate of $1000 \mathrm{gpm}$ through a piping system, a hydraulic power of $60 \mathrm{hp}$ is required. Determine the required pump head, the torque of the driving motor, and the estimated impeller diameter if an $1800 \mathrm{rpm}$ motor is used.