In recent years, the control valve industry has seen an important debate about the validity of limiting the valve trim exit velocity head to a maximum of 480 kPa in gas and steam applications. This velocity limitation is assumed to provide an acceptable noise level and avoid problems that arise in control valve gas and steam applications. However, in a very large number of applications, adopting a velocity limiting approach may require the use of expensive multi-stage or multi-turn trim designs. The purpose of this article is to demonstrate that low noise levels can be achieved without following this overly conservative and expensive trim exit velocity head limitation. Also, this article will show that having a trim exit velocity head lower than 480 kPa will still generate a very high valve noise level if the valve outlet Mach number is high.
MASONEILAN (2004) Valve Noise Prediction vs. Velocity Head Limitations In Gas Applications