Abstract: A test rig for testing the flow characteristics of ball orifice is introduced. Experiments on the flow characteristics of ball orifices with different structure parameters are carried out. The experiment results show that when ball seat’s half cone angle is 45°, chamfer length less than Rcosa/4, the ball orifice has relatively stable flow coefficient，about 0.9～1.0, and has good ability to inhibit flow saturation under all test openings and Reynolds numbers. It is also obtained from the experiment results that the chamfer angle of the valve seat has great influence to the ball orifice’s flow-pressure differential charact-eristic, however the chamfer length influences less.

Key words: Ball valve, Flow characteristics, Flow saturation, Water hydraulics