Lecture 21: Minor loss, kinetic energy correction factor
In general, loss in the globe valves is more than that in gate valves, because of the fact that fluid changes its direction sharply in the former. The globe valves are preferred over gate valves because of better flow-control.
Losses also occur in flange or weld joints connecting two pipes or fittings. Losses are also accounted for in diverging or converging nozzles or expanders, or where there are geometrical changes:
(Fig. 21b)
Apply mechanical energy balance between 1 and 2:
(assuming velocity profiles are uniform over the cross- sections at 1 and 2)
One can also apply continuity and momentum-balance equations between ‘1’ and ‘2’:
(CV is marked with dotted line) 
