Analysis of fitting noise propagation in lightweight steel constructions and design solutions for their prevention (AFINOPRO) : final report

This project aimed at studying systematically the propagation of sound generated by fitting noise in light gauge walls and their basic combinations following EN ISO 38221 'Laboratory tests on noise emission from applications and equipment used in water supply installation' using an installation noise standard (INS). An important result concerns the propagation of fitting-induced vibration energy through light gauge walls, which do not run face to face from the wall as expected but mainly over the top and bottom U-profile of the wall. The practical target consisted in finding solutions for material and mass combinations as well as optimal connection between walls creating rooms so that the sound propagation of noise generated by commercial non-classified fittings is reduced to less than 30 dB, the sound level value of whisper. Non-classified customary fittings, the most common group, produce a sound level of 36 dB at a flow of 25 l/min Using the results of the project the noise level can be reduced to 30 dB and better independence created for the expenditure wanted and an improved wall design. The project results offer the possibility to lower the input noise level by 16.8 dB. Therefore the sound level of a customary non-classified source of 36 dB should be reduced to less than 20 dB, the sound level of low breathing. By integrating an all-steel primary silencer developed in the project directly behind the fitting an additional reduction of 6.3 dB can be achieved.