Sigrist Design has a range of silencers to reduce noise levels.
One of our products is the rectangular silencer.

TEST METHODS

Test methods are in accordance with ASTM standard E477-80
(Standard Method of Testing Duct Liner Materials and Prefabricated Silencers
for Acoustical and Airflow Performance).

The following tests are performed on attenuators:
- Static Insertion Loss in dB
- Dynamic Insertion loss in dB
- Self-generated Airflow Noise in dB
- Pressure Loss with Airflow

STANDARD CONSTRUCTION

This standard construction is suitable for use up to a maximum pressure of 4 KPa.
-casing shall be constructed from prime quality pre-galvanised mild steel sheet, and will be the following
thicknesses: -1.0 mm up to 1000 mm
-1.2 mm up to 1000 mm to 2400 mm
-1.6 mm over 2400 mm
The case will be in one piece up to 1500 mm in length, over this the case may be made in two pieces although the acoustic splitters will always be made in one continuous section.
-end flanges: shall be either rolled steel angle section or knock-on type
-attenuating splitters: shall be arranged within the casing to provide optimum acoustic and aerodynamic
performance by the use of asymmetric thickness and spacing of the splitters.
The splitters shall be constructed from 0.9 mm pre-galvanised sheet steel and retained within the casing by
either rivets or self tapping screws.
The acoustic infill shall be retained with 0.6 mm perforated pre-galvanised steel sheet.
Acoustic infill shall be either fibreglass or rockwool suitable faced to prevent fibre erosion at passage velocities
up to 40 m/s.

CARE AND MAINTENANCE

Being a static item of equipment once installed there is no regular or periodic maintenance to carry out on duct mounted attenuators located inside the building. Inspection for corrosion would be part of a long term program and should be commenced at a time suitable to the operating environment. If the air stream is subject to a heavy dust load than a regular internal inspection of the perforated metal for dust build up should be carried out.
The splitters can be cleaned in most cases by brushing and vacuuming the perforated metal. Oil or grease build up should be removed by steam cleaning.