Pressure drop due to pipe fittings can be estimated by the equation, , where, Le = equivalent length of straight pipeline which will incur the same frictional loss as the fitting and D = diameter of the fitting. The value of (dimensionless) for 45° elbow and 180° close return bends would be respectively around

• 5 and 10
• 45 and 75
• 180 and 300
• 300 and 500