Sound insulation of technological pipelines in premises

Abstract

The paper describes a case when technological pipelines run through silent premises from one wall to another. If a certain medium (air or any liquid) is moving in pipelines, their walls propagate noise into silent premises. In addition, sound may also propagate in pipelines from the noise source, which is located quite far away, at the end of the pipeline (e.g., a ventilator or compressor). Also, in dependence on the velocity of the medium moving in the pipeline, various sounds (noise) appear in the medium itself.

As it was proven in our previously published reports, sound in the pipeline propagates quite far away, radiating a considerable part of sound power through pipe walls.

For abatement of noise caused by such pipelines, it is recommended to apply cylindrical shells. The general characteristics of sound insulation of the cylindrical shells were also described in the said reports. The efficiency of sound insulation of cylindrical shells depends greatly on the reinforcement of the shell and its contact with the pipeline itself. For that purpose it is possible to propose many ways for fastening of cylindrical shells. In this paper we shall analyze one of these methods.

The formulae obtained in the theory here presented make it possible to evaluate the efficiency of the method used for reduction of noise from technological pipelines that are located between two rigid partitions (walls).

In the case under consideration the cylindrical noise source, placed between the two rigid screens, may be insulated by a cylindrical shell, the efficiency of noise reduction of which is evaluated theoretically. When identifying the sound insulation of the cylindrical shell, many factors that have an effect on the determination of insulation properties have been evaluated. Here it was established that sound insulation consisted of two parts. The first part represents the indicated value of sound insulation of an infinite shell. The second part contains the dependence of sound insulation on the angle between the direction angle value and plane.