Noise from flowing fluids can be a problem in many production processes. Control valves can sometimes be the source of some of the noise being generated. This pipeline noise is unfavorable to personnel safety, regulatory compliance, and plant reliability. With the demanding challenges from day-to-day operations, an unpredictable future, and nearing deadlines for sustainability goals, how do you address this challenge?
In an on-demand webinar, Innovations in Aerodynamic Noise Attenuation in Control Valves, Emerson’s TK Arasu shares his expertise in severe service valves as he explores control valve-related noise and how next generation Fisher™ Whisper™ technology can help you reap the benefits quieter operations.
From a personnel safety perspective, the louder and longer plant staff is exposed to high levels of noise beyond 85 decibels (dBA), the more likely their hearing will be damaged. Contributors to this aerodynamic noise include:
- Turbulence created in the flow of gas or vapor flows through a control valve
- Flow path, flow obstructions, rapid expansion or deceleration of flow, and flow direction changes
- High pressure drops
TK notes how noise can be treated at the source through proper valve sizing, flow separation and jet management, and shifting noise frequencies out of the audible range.
The type of trim used in control valves can greatly reduce the aerodynamic noise generated by the fluid passing through the control valve. TK notes that they key to effective trim designs is proper jet management through small holes in the trim. This management is both for the individual jet streams created as well as the interactions between jet streams. This design can both lower noise generation and increase the frequency of the noise to drive it out of the audible range.
Smaller jets raise the frequency, increase transmission loss, and reduce external noise levels. These jets will expand as the differential pressure across the valve increases causing greater interactions among the jets. These interactions increase the noise levels.
In line with proper jet management, proper body design is critical. The Whisper I, Whisper III, and WhisperFlo trims are all compact enough to easily allow reasonable valve body designs maintaining sufficient flow area. Additionally, special valve body designs allow for extra flow area to help noise attenuation.
The next generation Whisper technology in Fisher Globe valves incorporates a lattice trim design, made possible by additive manufacturing technology. The Whisper NXG trim creates very minimal shear regions as the flow is dispersed flow. This innovative design means no hole spacing and provides greater flow capacity.
For Fisher Vee-Ball valves, the Whisper NXV trim enabled by additive manufacturing has unlocked trim geometries which improve the ability to manage flow and shift frequency. With traditional manufacturing methods, extra space may be needed around the trim in order to manufacture and assembly. The Whisper NXV trim fills up the entire ball leaving no gaps with a smooth inlet contour. This design significantly reduces the unmanaged turbulence through the valve.
TK also shared the Fisher WhisperTube technology to reduce noise in pipeline flow. Visit the blog post, Reduce Fluid Flow Noise Without Pressure Drop, to see a demonstration of this technology in action.
To learn more about ways to better protect hearing in your facility, watch the on-demand webinar and visit some of the links above in the post.
