See:
http://www.engineersedge.com/fluid_flow/head_loss.htm
http://www.engineersedge.com/fluid_f...s_equation.htm
http://www.engineersedge.com/fluid_f...nor_losses.htm
http://www.engineersedge.com/hydraul...sure_10054.htm
http://www.engineersedge.com/fluid_f...ction_loss.htm
http://www.engineersedge.com/fluid_f...le_content.htm