acoustics5 · Contractor Detail Drawing · Acoustic Design Basis

HVAC Silencer Installation Details

The duct silencers are the controlling acoustic elements in the HVAC system. Each run must keep the stated straight lengths, hanger spacing, and plenum insulation so the calculated attenuation is actually achieved on site [AC].

Run Count
5 runs
Longest
Run A · 1500 mm
Critical Branch
B2 (Control, re-rated)
Hangers
600 mm max spacing

Run A — VO Live

1500 mm · 40 dB · 1.5 m/s

Longitudinal Cross-Section

1500 mm 50 mm ProRox lining 40 dB attenuation target Velocity: 1.5 m/s

Installation Position

IDU-04 ceiling unit 300 mm straight duct before inlet 150 mm straight duct after outlet [AC] Silencer must be thermally insulated in plenum

Run B — IDU-03 Trunk

1000 mm · 25 dB · 2.0 m/s

Longitudinal Cross-Section

1000 mm 25 dB attenuation target Feeds B1 and B2 branches Velocity: 2.0 m/s

Installation Position

IDU-03 unit (Control only) 300 mm straight before inlet Branches split to B1 and B2 after trunk section

Run B1 — Control Room Branch

500 mm · 15 dB · 2.0 m/s

Longitudinal Cross-Section

500 mm 15 dB attenuation Control branch silencer

Installation Position

300 mm straight before inlet 150 mm straight after outlet Branch from Run B trunk toward Control Room diffuser line

Run B2 — Control Branch (former Editing)

300 mm · 10 dB · 2.5 m/s max

Longitudinal Cross-Section

300 mm 10 dB attenuation target Velocity: 2.5 m/s max Retained / re-rated for Control

Installation Position

300 mm straight before inlet 150 mm straight after outlet Run B2 retained/re-rated for Control; former Editing branch capped at trunk

Run C — Video/Podcast

1000 mm · 25 dB · 2.0 m/s

Longitudinal Cross-Section

1000 mm 25 dB attenuation target Velocity: 2.0 m/s Video/Podcast branch

Installation Position

IDU-05 ceiling unit 300 mm straight before inlet 150 mm straight after outlet [AC] Thermally insulate silencer casing in plenum

IDU-03 Note

[HP] Confirm former Editing branch is capped before close-up

IDU-03 serves the Control Room only. The former Editing branch is capped and sealed at the trunk, so no crossover duct remains. Run B1 and Run B2 both feed Control; B2 is retained and re-rated for Control (NC-18). Verify the capped branch is fully sealed at the trunk before close-up [HP].