Emerson’s new silencer protects industrial workers from gas process noise — without impacting process flow

by Brianna Crandall — March 25, 2022 — Global technology and engineering company Emerson has introduced the Fisher WhisperTube Modal Attenuator for noisy gas or vapor applications in a wide range of industries. The modal attenuator is a full-bore silencer device offering 15-decibel sound suppression to reduce noise inside pipes produced by sources upstream, such as control valves or other devices. It is installed downstream of these types of devices in place of a pipe spool piece, generates no additional pressure drop, and has no impact on process flow, says the company.

Emerson Fisher WhisperTube Modal Attenuator

Emerson introduced the Fisher WhisperTube Modal Attenuator for noisy gas or vapor applications in a wide range of industries. Image courtesy Emerson

Industrial users have long searched for a solution to reduce process piping noise, but until now all solutions have generated significant pressure drop, reduced flow, and/or introduced obstructions, according to Emerson. This has led some users to install acoustic insulation to pipe sections to reduce noise, but this can be very costly and cumbersome to install, and it does nothing to reduce internal piping noise.

The modal attenuator reportedly addresses these and other issues with a drop-in solution, improving worker safety and regulatory compliance, while reducing the risk of damage to downstream equipment due to high noise levels internal to piping.

Emerson silencer

The silencer consists of acoustic cavities of varying sizes surrounding a full bore perforated tube. Each cavity generates destructive interference over a range of frequencies to provide significant noise reduction across a broad spectrum. Image courtesy Emerson

Leading applications for the silencer include those where upstream process flows are changed by control valves, pressure relief valves, pumps, compressors, and other devices that generate noise. Many of these devices must be installed in lengths of piping with no-flow restrictions downstream, and the modal attenuator works particularly well in these applications because it introduces no such restrictions.

Unlike other noise suppression solutions, the modal attenuator does not introduce an obstruction into the piping, so it can be used in applications where particulates are suspended in process flows, and/or where pigging is required for cleaning and maintenance.

WhisperTube devices are offered in sizes from 2” to 12”, with American Society of Mechanical Engineer (ASME) flange ratings of Class 150, 300 and 600. Pressure ratings match the flange rating sizes, and the maximum temperature is 700 degrees Fahrenheit.

For more information about the Fisher 6060 WhisperTube Modal Attenuator, visit the Emerson website. The company provides innovative solutions for customers in industrial, commercial and residential markets.