Cavitation is changed phenomena vapor phase from liquid in fluid flow. Phase can change caused pressure drop or temperatur increased. Pressure drop occurred because acceleration flow caused reduction flow area. Cavitation can be occurred on pump suction, pump impeller and valve in piping system. Cavitation indication by raised vapor bubble, noise, and vibration on pipe.

            Numerical study is used to identify cavitation process on gate valve using Fluent 6.2 software. Flow simulation under steady, unsteady and cavitation condition. The fluid is water with variation valve-open ratio, velocity inlet and temperatur. Cavitation is analized from result visualisation whose pressure contour, vapor volume fraction and velocity vector.

            This study resulting cavitation happen for valve-open ratio D/Do=0.29 and D/Do=0.42 with temperature 80