500 gal/min (30 l/s) of 100 degree F (40 degree C) water flows through 300 ft (90m) of 6-inch Sch 40 steel pipe. The pipe contains two 6-inch flanged, regular 90 degree steel elbows, two full-open gate valves, a full-open 90 degree angle valve, and a swing check, forward flow valve. The discharge is located 20 ft (6 m) higher than the entrance. What is the pressure difference between the two ends of the pipe?