Page Bernoulli’s Theory H   P v h w g H total head metres w force of gravity on m of fluid N h height above datum level metres v velocity of water m per second P pressure N/m or Pa Loss of Head in Pipes Due to Friction Loss of head in metres Lv f d2g L length in metres v velocity of flow in metres per second D diameter in metres f constant value of .0 in large pipes to .0 in small pipes Pump Calculations If efficiency of pump efficiency of pump then                         n D Q Q × × n D n D h h × × n D n D kW kW × × n D where kW pump power required h head developed by pump m D impeller diameter mm n pump speed rpm Q quantity pumped L/min Center of Pressure on a Submerged Surface c.g G c.p c.g H I y AH sin θ sin θ where y c.p distance from liquid surface to the center of pressure m I G second moment of area around the centroid of the submerged area m A submerged area m H cg height of liquid above the centroid of the submerged area m θ angle from the horizontal of the submerged surface