Figure 1
The diagram contains four circular pipe cross-sections labelled 1 loop, 2 loops, 3 loops and 4 loops. A filled circle represents flow down the pipe, and a cross represents flow up the pipe. A ring marks the inlet, and another ring marks the outlet. For 1 loop, the outlet surrounds a cross on the left, while the inlet surrounds a filled circle on the right. For 2 loops, one filled circle appears at the top, one cross at the left, the inlet surrounds a filled circle at the right and the outlet surrounds a cross at the bottom. For 3 loops, filled circles appear at the upper left and lower left, crosses at the left and upper right, the inlet surrounds a filled circle at the right and the outlet surrounds a cross at the lower right. For 4 loops, filled circles appear at the top, lower left and lower right, crosses at the left, upper right and bottom, the inlet surrounds a filled circle at the right and the outlet surrounds a cross at the upper left.Pipe arrangement for different U-loops in a pile cross section