A novel laboratory method to measure the efficiency of acoustic insulation for pipes

摘要

Traditionally the acoustic transmission loss of pipeline insulation has been measured inaccordance with the ISO 15665 and ASTM E1222 procedures which required a largereverberation chamber, 4m or longer section of a metal pipe, large area of the materialspecimen and a long preparation time. This work proposes a new method of measurementof the transmission loss quality of a pipeline insulation which is based on a compactlaboratory setup. It consists of a short section of an insulated metal pipe, impact hammer,two accelerometers attached to the internal pipe wall and a laser vibrometer projected onthe external wall of the pipe insulation. The proposed method determines the ratio of thevibration velocity measured on the external wall of the pipe insulation and that measuredon the internal wall of the metal pipe. The results for a standard poro-elastic insulationlayer applied to a 12” pipe agree closely with that measured in accordance with the ISO15665 procedure and predicted by a finite element model. The proposed method providesan alternative to ISO 15665 because it is able to evaluate rapidly the vibro-acousticinsulation performance of a large number of small material specimens.