CYLINDRICAL SILENCERS For use with Axial Fans

Construction: Casings are of rolled, pre-galvanised sheet steel with spun end rings incorporating tapped inserts for fixing. Suitable fixing screws are provided with all steel silencers. The absorbent material is acoustic grade mineral fibre with an erosion resistant facing. It is protected and contained by a pre-galvanised perforated sheet formed to match the fan diameter. Cylindrical silencers shall be suitable for air pressures up to a maximum of 1000 Pa. For duct pressures in excess of 1000 Pa. please enquire. A Melinex Lining (variant code M) can be supplied for critically clean applications such as hospitals to ensure no fibre migration. The lining may also be used in moisture or grease laden conditions, such as kitchen extract systems where material is used in the ingress of grease etc. into the acoustic media. The use of the lining also allows the silencers to be low pressure steam cleaned. Some reduction of attenuation due to the lining will be experienced.

Performances: Are derived from tests to BS848. Measurements of fan noise are made with and without the silencer in position. The difference between the recorded levels is the dynamic (with airflow) attenuation or insertion loss of the silencer. Type B silencers may be directly coupled to both inlet and outlet flanges of the fan. When type C silencers are directly coupled to the fan flanges they are most effective on the outlet. A spacer duct of 1D length between the fan inlet flange and a type C silencer is necessary to ensure maximum performance. Note: C type silencers mounted close to a fan may affect the aerodynamic performance.

Size Range: Type B silencer bore diameters range from 280 mm to metric range, 6” to 75” imperial range in lengths equal to or twice the bore diameter (1D or 2D) 6” to 9.5” are available in 1.5D lengths only. Pressure loss for type B silencers is the same as a plain duct. Type C silencers have a centrally mounted absorbent pod in the airway for increased attenuation. The pressure loss due to the pod is shown on the chart below. The diameter range is 315 mm to 2000 mm metric range or 12” to 75” imperial range.

Fume Handling: Stainless Steel, PVC or Polypropylene construction is also available for corrosive atmospheres. Please send details of the application with the enquiry.

Marine Use: The construction of standard silencers has been satisfactory for below decks on ships and oil rigs and a specially strengthened design is available for other locations, please enquire.

Temperature Range: Standard silencers are suitable for temperatures from - 40°C to +200°C. When moisture resistant lining is used the continuous air handling temperature is limited to 80°C. Special treatments enable silencers to operate at temperatures up to 600°C. For smoke applications, please enquire.

Finishes: Standard finish is galvanised zinc coating to BS 2989 Z2. Other finishes including epoxy paint are available to special order.

Mounting: Galvanised steel mounting feet , anti-vibration mounts and matching flanges corresponding to those supplied for Aerofoil fans are available.