Double Elbow:

This offset is used when the deviation is so small that it does not allow the use of traditional pipe elbows with an angle of 45 degrees. They guarantee a smooth transition of water in the change of orientation, minimizing hydraulic resistance, which avoids increasing energy consumption in the pumps. The fact of using elbow sectors with an angle of less than 45 degrees, allows both sectors to be cut from a single elbow of 90 degrees, which minimizes material consumption.