Heiichiro Ohkawa

Experimental study on sound and vibration generated by a valve in a water piping system

Various acoustic troubles are caused by the structure‐borne sound generated by water piping systems connected with pumps at hotels or condominiums. Sound and vibration generated by water piping sytems are uncomfortable factors in living environments which require silent conditions. In order to predict and control sound and vibration generated by water piping systems, it is necessary to obtain some data about acoustic characteristics of sound and vibration sources such as pumps and valves. Vibration of pipe walls and sound in water generated by valves according to flow quantity obtained by pump rotation control and valve control, and also water temperature, were measured, and the basic tendencies of sound and vibration characteristics were obtained. In this paper, these investigative results are described.

Studies on sound and vibration generated by household appliances. II. The determination of vibromotive force of waste disposers by a comparison method

The household food waste disposer is attracting attention as one of the leading disposal systems in Japan, and it is thought that disposers will be installed in many condominiums from now on. Sound and vibration which are generated by a disposer will come under fire as a new noise source. To popularize the disposer in Japan, reduction of the sound and vibration which are generated by disposers is an important matter. In this paper, as a standard method for measurement and evaluation of the vibration which is generated by disposers, the determination of the vibromotive force level of disposers is studied by the comparison method. As a result, it is clear that the vibromotive force level of a disposer is influenced by the kinds of food waste, but the frequency characteristic is relatively unaffected, a behavior similar to that found for sound power level.

Studies on sound and vibration generated by household appliances. I. The determination of sound power level of a waste disposer by the comparison method

A household food waste disposer is attracting attention as one of the leading disposal systems in Japan, and the possibility that a disposer will be installed at many condominiums from now on is under consideration. Sound and vibration, which are generated by a disposer, are being considered as a new noise source problem. To popularize the disposer in Japan, the reduction of the sound and vibration generated by the disposer is an important matter. In this paper, as a standard method for measurement and evaluation of sound generated by the disposer, the determination of sound power level of a disposer by a comparison method in a hard‐walled test room is studied. As a result, the accuracy of measurement for the sound power level of the disposer is practically confirmed. Also it is clear that the sound power level of the disposer is influenced by the kinds of food waste, but frequency characteristics are scarcely affected.