A new water piping system is being designed for an apartment complex. The supply of water to this complex must provide 1200 gallons/min at a pressure of 25 psi and will come from the large diameter main city supply line which is maintained at 65 psi. We want to determine the appropriate pipe diameter to connect the city line to the apartment complex line. We are going to use a plastic material for our pipe that is known to have an equivalent roughness of 5 x 10-7 ft. We also know that we are going to use 100 ft of pipe, 4 threaded 90° elbows, 10 threaded unions, and a swing check valve or forward flow. The elevation difference between the main source and the apartment source is 10 ft. Determine the pipe diameter to use.