This part of IEC 60534 established a method to predict the noise generated in a control valve by liquid flow and the resulting noise level measured downstream of the valve and outside of the pipe. The noise may be generated both by normal turbulence and by liquid cavitation in the valve. Parts of the method are based on fundamental principles of acoustics, fluid mechanics, and mechanics. The method is validated by test data. Noise generated by flashing flow is not considered in this standard.
The transmission loss (TL) equations are based on analysis of the interaction between the sound waves inside the pipe and the coincidence frequencies in the wall of the pipe taking into account that commercial pipe tolerance allow a relatively wide variation in the thickness of the pipe wall. Ideal straight piping is assumed.
The nethod can be used with all conventional control valve styles including globe, butterfly, cage-type, eccentric rotary, and modified ball valves. Test so far have only been conducted with water. The applicability of this method for fluids other than water is not known at this time.