An ultrasonically operated valve a source of ultrasonic energy for excitation of a pressurized liquid. The vibration of the ultrasonic horn imparts a pulsing of the pressure of the liquid within the valve. Selection of a sealing mechanism that responds at a different natural frequency than that of the valve body causes the sealing mechanism to unseat and therefore to enable liquid flow. The sealing mechanism will stay unseated as long as the source is imparting energy to the system and therefore inducing pressure pulses in the liquid thus keeping the sealing mechanism away from the valve seat.