Cylindrical Silencers
Axial Fans are installed with cylindrical silencers to reduce the sound to an acceptable level. Cylindrical silencers are commonly used as it can be connected directly to the round inlet or discharge side of a fan.
Rosenberg cylindrical silencers are available in two types:
- RS – open cylinder design;
- RSM – fitted with an concentric pod, producing better attenuation.
Three standard length of silencers are available:
- One diameter length: RSM-1D and RS-1D;
- One and half diameter length: RSM-1.5D and RS-1.5D
- Two diameter length: RSM-2D and RS-2D
Silencer casings are of rolled, pre-galvanized steel sheet 1.2mm thick with end flange ring incorporated with self-insert nuts for easy installation.The ends of the silencers are drilled and tapped to match flanges of Rosenberg axial flow fans.
The absorbent material is an acoustic grade non-combustible mineral wool encassed by a galvanized perforated steel sheet. When a pod is fitted, it is of perforated metal, retaining an infill of acoustic grade mineral wool.
The silencer constructional intergrity is suitable for pressure up to 2500Pa.
For critically clean and wet conditions, e.g. hospitals and kitchen exhuast or moisture resistance area, Melinex lining of the acoustic infill can be provided to prevent the ingress of moisture or grease. A small reduction of attenuation in the higher frequencies due to this lining are expected.
RSM and RS silencer are available from inner diameter of 315mm to 1600mm.
Acoustic performance data shown are obtained with test conducted in accordance to ISO 7235 standard. The silencer attenuation is defined as the dynamic insertion loss. The values quoted in the tables attached represent the difference between the sound power level, dBW of a fan and silencer combination and the dBW rating of the fan alone. Dynamic insertion losses are the attenuation recorded under working conditions.
RS silencer have a pressure drop equivalent to a similar length of plain ducting with the same diameter.
RSM silencer dynamic pressure loss is:
= 0.5 x density of air x ( K factor) x (Face velocity)2
= 0.6 x (K factor) x (Face velocity)2
K factor are given in the attached table. Alternatively the pressure loss can be obtained from the pressure loss chart attached.
Standard silencers are suitable for temperature from -400c to 2500C.
Standard finishing with galvanized zinc coating.Other finishing like epoxy paint are available with extra cost upon request.
