Quick Guide to HVAC Duct Silencers

Heating, ventilation and air-conditioning (HVAC) systems are ubiquitous in industrial, commercial and medical environments – but equally ubiquitous and well known to anyone who has worked in such environments is the noise given off by HVAC air ducts.

IAC, in conjunction with acoustic consultants, engineers and contractors, has developed a range of different duct silencer technologies to meet the various specific noise-management requirements of end-users.

Ultimately, user experience and performance will vary between different designs. The details are outlined below.

Rectangular and Circular Silencers

This variety of silencer is generally suitable for all conventional applications, including air-handling units, mixed flow fans, inline centrifugal fans and roof exhaust ducts. These duct silencers feature rounded solid noses, specially shaped to minimise pressure drops and thus avoid performance compromise. Inside the duct-style casing are sound-absorbing acoustic baffles, with proportions optimised for optimum performance. Both the circular and rectangular silencers are precision-engineered to cancel noise in the lower octave band frequencies of 63Hz, 125Hz and 250Hz.

Clean-Flow Silencers

Designed for environments demanding a high degree of hygiene and cleanliness, such as in medical or micro-circuitry clean rooms, Clean-Flow silencers are rectangular in form but contain specialised linings over the fill material to prevent particulate matter entering the air stream via erosion. Certain features of the internal construction of Clean-Flow silencers guard the lining against premature failure and work to sustain the specified aero-acoustic performance rating of the silencer throughout its service life.

Diffuser Silencers

The construction of diffuser silencers features an internal diffuser cone inside an external square jacket casing, giving them the function of aerodynamic regain devices as well as being highly effective silencers. Specially designed for installation over the outlet of axial fan systems, IAC offers optimised diffuser silencers for variable vane and controllable pitch van axial fans. The fill material of these silencers consists of glass fibres or inorganic minerals of sufficient density to achieve the desired acoustic attenuation.

Packless Silencers

Engineered for environments where a high degree of airflow management is required, packless silencers are most appropriately applied in corrosive, flammable or ultra-clean settings, including circuitry and pharmaceutical manufacture, operating theatres and clean-room assemblies. IAC offers packless silencers in both rectangular and tubular forms.

The rectangular form does not contain any fill material and is extremely easy to drain and clean, making it best suited for chemical plants, hazardous-material processing centres, refineries and engine test cells.

Circular packless duct silencers are optimised for use over circular duct systems with small outlet diameters, such as those seen on fume hoods.

IAC has established an outstanding reputation over the past 60 years as one of the world’s leading providers of systems and products designed for noise control and attenuation. If you would like any additional information on the noise solutions that we have to offer, please don’t hesitate to get in touch.