This part of IEC 60534-8 includes the method for measuring the sound pressure level due to liquid flow through a control valve and the method for determining the characteristic increase in noise due to the onset of cavitation. It also defines the equipment, methods, and procedures required for laboratory measurement of the airborne sound necessary to determine these characteristics.
Two methods are provided for testing the noise generating characteristics of control valves. The first is a uniform method of measuring the radiated noise from the valve and the associated test piping, including fixed flow restrictions through which the test fluid (water) is passing (see Note 1). The criteria for determining the sound pressure level of the valve under consideration are established.
The second method involves measuring the sound pressure levels within pipe systems upstream and downstream of the valve under fixed operating conditions. Since this eliminates inaccuracies due to pipe transmission, it is preferred for evaluating the acoustical characteristic of valves.
The noise characteristics to be determined are useful:
a) to determine the acoustical characteristics of valves and valve assemblies, and the characteristic pressure ratio factor x Fz of a control valve;
b) to predict valve noise for given process conditions;
c) to compare the performance of different valves and various measuring results;
d) to plan measures for increasing service life and noise reduction;
e) to determine possible adverse effects on ultra-sonic flow meters;
f) to enable proper sizing of sound absorbers.
Note 1: Test fluids other than water or valves without downstream piping are not within the scope of this section of IEC 60534-8.
Note 2: The factor x Fz is used in a noise prediction method covered in IEC 60534-8-4.
