These results indicate that the losses in a cascaded elbow with while losses in bend are much lower.
The pressure gradient in the brass pipe for fully developed flow at this velocity is: 0.081 in of water
per foot. For the sound absorbing pipe the loss is
10
0.81 0.06 = 0.075 in of water per foot. Losses in the
sound absorbing pipe are, therefore, slightly less than in the brass pipe.
It is convenient to express the losses due to each fitting as loss coefficient K, (p.385).