Conventional extract fan silencing is not only subject to clogging, but can also increase backpressure, reducing system efficiency - not what you need from an extract system that is intended to protect operators from fume hazards.
However, there are elegant, innovative and low-cost solutions that:-
- reduce fume or dust extract LEV fan noise to reduce both environmental complaints
- reduce occupational noise hazards
- can substantially improve LEV performance and operator safety
Solving the low frequency noise problem
A large weld booth fume extractor fan system generated high-level low-frequency tones at 35Hz and harmonics that caused extensive complaints in nearby offices. Diagnostic measurements proved that the major problem was an in-duct standing wave resonance in the manifold that was amplified by panel resonances in the filter enclosure.
The engineering solution involved:-
- designing an aerodynamic insert that was fitted in the ductwork to reduce turbulence
- fitting an acoustic absorbent plug into an end cap to create an anechoic termination to destroy the standing waves
- applying stiffening ribs to the filter enclosure to detune the noise radiating panels
These measures were fitted within a single day at very low cost to eliminate the low-frequency tones (a 30dB reduction).
Improving the LEV weld extract system performance
The first step in our approach to attenuate LEV fan noise is to develop modifications to improve the system efficiency as this also reduces noise (noise is wasted energy).
In this case, the aerodynamic modifications we designed to cut the noise also dramatically improved the fume extract fan system efficiency, improving safety and reducing running costs.
This approach based on our expertise in fan systems can be used to improve LEV extract efficiency, even where noise is not an issue...
View the detailed guide to fume and scrubber extractor fan noise reduction and silencing techniques.
