Amixture of contains 85 mol% methane and rest propane, is being sent through a horizontal schedule 40, 6-inch diameter cast iron pipe at a flow rate of 20 kgmol/h. the pressure at the pipe inlet is 2.45 bars and temperature is 25°c. the pipe length is 2000 m. the pipe is followed by gate valve (half-open) having similar inner diameter and material as pipe. find the overall pressure drop. assume no heat