Just starting to look at a project involving a requirement for a number of control valves for propylene gas,inlet pressure 14 barg,outlet pressure 2 barg, done a sizing calculation and the software indicates supersonic flow with a decibel level of 90@ 1 metre,valve size is 1O0mm with the outlet size opened up to 200mm using a reducer,the software indicates the use of a 3 stage cage trim,dont have the flow to hand as I am doing this from home,but available tomorrow

Does anyone have any experience of this sort of application,things to look out for etc,Would a differnt trim help?,is it benificial to keep away from supersonic flow and what are the possible negatives,the valve characteristic is equal percentage and the actuator fails open.

You do not mention the purpose of this study and your position in the project.

Before going into details for any technical valve solution, I have always found it sensible to look into 'what is available at already existing (standard) commercial solutions' and what do the suppliers of the commercial solutions suggest.

To make such a survey you will need not only to focus on the detailed components itself (in this case valves) but also purpose and overall target for the total application.

1. The flow will be sonic, not supersonic.
2. The noise of 90dBA can be mitigated by heavier wall piping downstream and/or insulation if lo-db trim is deemed undesirable.
3. Depending on flowrate, a v-ball with diffuser could reduce the noise below 85 dbA.  If flow and pressure drop are constant then a lo-db diffuser would be adequate.  There are many low-noise options.  Ask Fisher, Masoneilan, Valtek, Neles etc and they can guide you.
4. The 3 stage trim sounds overkill for the relatively low upstream pressure although they likely look at the pressure ratio.  I think a single stage drilled hole cage or grille should be able to lower the noise by 5 dBA.

MORE NEWS