Abstract: A method for purification of drinking water and other liquids includes providing a generally cylindrically-shaped open-ended tube for flow of the liquid therethrough, the tube comprising a transducer for converting electrical energy to acoustic energy, providing a liquid moving means for flowing the liquid through the tube, and providing an electrical power source for providing electrical power to the tube. The method further includes operating the liquid moving means to flow the liquid through the tube, and operating the power source to transmit ultrasound through the liquid in the tube to induce cavitation in the liquid in the tube. The cavitation inactivates microorganisms in the liquid.

Abstract: A method and assembly for pasteurizing and homogenizing low-viscosity liquids, the method including the steps of flowing the liquid through a tube comprising a transducer for converting electrical energy to acoustic energy, and providing electrical power to the transducer to generate ultrasound and to transmit the ultrasound through the liquid in the tube to induce acoustic cavitation in the liquid in the tube, wherein the cavitation so induced operates to inactivate microorganisms in the liquid and to reduce the size of fat globules in the liquid to a point at which the globules refrain from coalescing and rising to the surface of the liquid during the useful storage life of the liquid.

Abstract: The sonar transducer includes a metal core about which is situated a cylindrical piezoelectric ceramic ring element with paper interposed therebetween. In order to improve resistance to fracture resulting from mechanical shock, in one embodiment, the core is reduced in diameter, such that a potting compound can be situated between the paper and the ring. In a second embodiment, the ring element is divided into two individual, axially aligned cylindrical ring subelements with a gasket interposed therebetween.

Abstract: The sonar transducer is protected from explosion shock by a variable impedance device, such as a metal oxide varistor, connected in parallel with the energy conversion component. The varistor normally has a very high electrical impedance, but becomes conductive upon application of the very high voltage output of the energy conversion component as a result of a rapid increase in mechanical energy, such as would accompany an underwater explosion in the vicinity of the transducer, to limit both voltage and current to a safe level so that the transducer can thereafter operate within acceptable parameters.