The mechanical meaning of the
valves is a device which uses in controlling the passage flow of fluid in a
pipe which is used for the industrial purposes different name are given
according to the different mechanical types of a valve.
Butterfly is metal handle mounted
o on the top of the rod handle which direct the direction of the valve either
parallel or perpendicular the flow of the liquid and pressure depend on the
direction of the valves, in a butterfly valve consist a rotating circular plate
or a pair of hinged semicircular plates, attached to a transverse spindle and
mounted inside a pipe in order to regulate or to prevent the flow.