to control the pressure variations due to rapid changes in the pipe line flow

to eliminate water hammer possibilities

to regulate flow of water to turbines by providing necessary retarding head of water

all of the above

real fluid

ideal fluid

newtonian fluid

non-newtonian fluid

avoid the tendency of breaking away the stream of liquid

to minimise frictional losses

avoid the tendency of breaking away the stream of liquid and to minimise frictional losses

none of these

atmospheric pressure

gauge pressure

absolute pressure

none of these

zero

minimum

maximum

none of these