Attenuators 2021-04-21T13:29:28+00:00

The Need for Attenuators

All modern buildings contain services that provide heat, water, light, power and ventilation. Often these services can create excessive noise, requiring attention from qualified and experienced engineers to resolve. Over many years we have developed a range of standard solutions and more bespoke solutions for situations where conventional products will not meet criteria. Using our own bespoke internally developed software and certified data enables us to confidently recommend a solution that resolves any noise issues. Uniquely over many thousands of our product installations, we have never experienced any failures in meeting specifications.

Our design team will be happy to give you advice and guidance on the best selection and orientation of our proposed and recommended acoustic solutions that minimise energy loss or system resistances, along with advising on space restraints met on sites.

Our Products

We have a range of standard products in our Attenuators offering including, but not limited to, our CP01 Series Circular Spigot Attenuators, CP03 Series Circular Fan/Flange Connected Attenuators (including a podded insert where higher noise reduction is required), R02 Rectangular Attenuators and our LP Acoustic Louvres range.

Our circular range is typically available from 100mm⌀ to 2000mm⌀, with larger diameters available on request, while we offer the rectangular range in any size in 1mm increments. However, larger modules are supplied as smaller modules to allow for transportation and easier handling for ‘on site’ installation.

For our louvre and attenuator ranges, we offer Bespoke selections that include mounting type, material grade, thickness or design. We can provide Stainless Steel (all grades), powder or chemical coating and even offshore specifications – please ask our sales team to quote for any special requests you may have.

CP01 Series

CP03 Series

R02 Rectangular Silencers

IP01 Limpet Fan Flange

IP03 Mounting Feet

LP Acoustic Louvres

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Technical Guides

NR Levels

Noise Rating Levels or NR Level Curves are developed by the International Organization for Standardization (ISO) and specify an indoor acoustic environment for different requirements of hearing preservation, speech communication and annoyance, in different applications.

Noise Rating values for different sound pressure levels are tabulated below and are the established sound pressure levels at different frequencies. Noise Ratings are then used to specify the maximum permissable sound power level at each frequency by selecting a single Noise Rating (NR) number. The use of Noise Rating – NR – is widespread across Europe.


dBA Guide

A noise level specified as a dBA level is a weighted logarithmic average of a set of frequency specific sound levels.

The weighting system is designed to adjust the sound levels to an approximation of the human ear response. The addition of the individual weighted values is designed to combine the sound spectrum into one single figure for comparitive purposes.