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Silencers & Acoustic Louvers | YONGFAN
Octave-Band Tested · Splitters, Micro-Perf & Louvers

Silencers & Acoustic Louvers: HVAC Sound & Pressure Control

HVAC acoustic equipment must reduce the required octave-band noise without consuming too much fan pressure or creating more airflow-generated noise than it removes.

Compare YONGFAN Splitter Duct Silencers (8–78 Pa loss, up to 45 dB @ 1,000 Hz), Micro-Perforated Panel Silencers (2–21 Pa loss, zero fibrous filler), Metal-Cased Splitters (200–350 mm splitters, up to 44 dB @ 2,000 Hz), Matrix Silencers, and Acoustic Louvers (L=300 mm outdoor plant attenuation).

Standard Splitter8–78 Pa · 45 dB @ 1 kHz
Micro-Perforated2–21 Pa · Fiber-Free
Thick Splitters200–350 mm · 120 Pa max
Acoustic LouversL=300 mm · Plant Intake/Ex
Select an HVAC Silencer Acoustic Comparison Matrix
HVAC duct acoustic splitter silencer installation
Octave-Band Noise Attenuation Insertion Loss · Pressure Drop Verification · Low Regenerated Sound
01 / Acoustic Physics & Penalties

Noise-Control Failures Begin When dB Reduction Is Selected Without Pressure Loss

A fan can meet its airflow schedule and still cause noise violations; adding a silencer chosen solely from headline dB ratings often causes severe aerodynamic starvation.

Silencer performance involves three interdependent quantities: insertion loss (noise reduction), pressure loss (aerodynamic drag), and regenerated noise (sound created by high-velocity air passing through baffles).

YONGFAN’s standard splitter silencer total-pressure loss rises from 8 Pa at 4 m/s to 78 Pa at 12 m/s, while providing up to 45 dB insertion loss at 1,000 Hz. Acoustic louvers (L=300 mm) exhibit much higher resistance: 275.8 Pa at 4 m/s to 1,487.2 Pa at 10 m/s.

Acoustic equipment must be engineered together with the fan curve, following octave-band insertion loss from 63 to 8,000 Hz rather than single overall dBA estimates.

Commercial fan plant room acoustic duct attenuation

ASHRAE Handbook — Noise and Vibration Control treats insertion loss, allowable pressure drop, silencer location, regenerated noise, and duct geometry as linked selection variables.

Octave-Band Insertion Loss

Evaluates noise reduction across 63 Hz, 125 Hz, 250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz, and 8 kHz octave bands.

63–8,000 Hz Spectrum

Aerodynamic Pressure Loss

Calculates exact drag (ΔPt Pa) at operating duct velocities (4 to 12 m/s) with verified drag coefficients (ζ = 0.2 to 1.0).

Velocity vs ΔPt

Self-Generated Sound

Verifies that airflow passing through silencer splitters does not regenerate background hiss exceeding room NC criteria.

Regenerated Noise Limits
02 / Product Architecture

Match the Acoustic Construction to the Noise Problem

Detailed technical features across standard splitters, micro-perforated silencers, metal-cased thick splitters, structural sections, matrix silencers, and acoustic louvers.
Family 01 · General HVAC Fan Noise 100 mm Splitter · 8–78 Pa · ζ = 0.9

Splitter Duct Silencer

Resistive dissipative acoustic silencer with 100 mm splitters filled with centrifugal glass wool, wrapped in alkali-free glass cloth behind φ4 mm perforated metal faces.

Insertion Loss35 dB @ 500 Hz · 45 dB @ 1,000 Hz · 32 dB @ 2,000 Hz
Aerodynamic Loss8 Pa @ 4 m/s · 35 Pa @ 8 m/s · 78 Pa @ 12 m/s (ζ = 0.9)
Construction100 mm splitters, rectangular W×H-L dimensions
Best FitGeneral AHU supply, return, and exhaust fan ductwork
Configure Splitter Silencer
Standard splitter duct silencer
Splitter Duct Series 100 mm Resistive Baffles · 45 dB @ 1 kHz · Low Resistance ζ = 0.9
Family 02 · Cleanrooms & Humid Air <1 mm Holes · Zero Fibers · 2–21 Pa · ζ = 0.2

Micro-Perforated Panel Silencer

Resonant acoustic absorber featuring sub-millimeter perforations (<1 mm) and zero fibrous media. Eliminates fiber-shedding risks and offers minimal resistance.

Zero FibersNo glass wool or mineral fiber; cleanroom and hospital safe
Ultra-Low Drag2 Pa @ 4 m/s · 9 Pa @ 8 m/s · 21 Pa @ 12 m/s (ζ = 0.2)
Moisture ResistantUnaffected by condensation or high-humidity airstreams
Trade-offModerate attenuation (~6 dB @ 500 Hz) compared to fibrous splitters
Configure Micro-Perf Silencer
Micro-perforated cleanroom acoustic silencer
Micro-Perforated Series Sub-Millimeter Resonant Holes · Zero Fiber Shedding · ζ = 0.2
Family 03 · High Broadband Attenuation 200–350 mm Splitters · 22–120 Pa · ζ = 1.0

Metal-Cased Splitter Silencer

Heavier acoustic construction featuring thick 200–350 mm splitters for strong broadband mid-to-high frequency attenuation in industrial and large commercial ductwork.

High Attenuation22 dB @ 500 Hz · 34 dB @ 1 kHz · 44 dB @ 2 kHz · 32 dB @ 4 kHz
Heavy ConstructionStructural angle/channel steel casing with baked enamel finish
Pressure Drag22 Pa @ 4 m/s · 71 Pa @ 10 m/s · 120 Pa @ 12 m/s (ζ = 1.0)
Best FitHigh-pressure industrial fans, central plant rooms, and chiller ducts
Configure Metal-Cased Silencer
Heavy duty metal-cased splitter silencer
Metal-Cased Series 200–350 mm Thick Splitters · 44 dB @ 2 kHz · Structural Enamel Casing
Family 04 · Outdoor Building Envelope Sound Control L=300 mm · Galvanized / Stainless / Aluminum

Acoustic Louvers for Plant-Room Wall Openings

Installed in exterior building facades and plant room wall openings to prevent mechanical noise radiating to property lines while allowing weather-protected air intake and exhaust.

Depth BasisStandard 300 mm casing depth with aerodynamic sound-absorbing blades
MaterialsHot-dip galvanized sheet, stainless steel, or architectural aluminum
Pressure Drag275.8 Pa @ 4 m/s · 529.6 Pa @ 6 m/s · 933.4 Pa @ 8 m/s
Face Velocity RuleKeep face velocity low (2–4 m/s) to prevent excessive pressure drops
Configure Acoustic Louvers
Architectural acoustic louvers on building facade
Acoustic Louver Series L=300 mm Depth · Weather Protection · Exterior Boundary Attenuation
03 / Specification Matrix

Acoustic Equipment Comparison Matrix

Performance boundaries, pressure loss ranges, and selection priorities across the YONGFAN acoustic lineup.
Product Main Acoustic Mechanism Documented Performance Boundary First Item to Confirm
Splitter Duct Silencer
 Resistive glass-wool splitter (100 mm)
8–78 Pa loss @ 4–12 m/s; up to ~45 dB @ 1 kHz
 Required octave-band attenuation spectrum
Micro-Perforated Panel Silencer
 Resonant micro-perforated panel (<1 mm), no fiber
2–21 Pa loss @ 4–12 m/s; ~6 dB @ 500 Hz
 Cleanliness / fiber-free / humidity requirement
Metal-Cased Splitter Silencer
 Thick resistive splitter (200–350 mm)
22–120 Pa loss @ 4–12 m/s; up to 44 dB @ 2 kHz
 Allowable fan static pressure budget
Structural Splitter Silencer
 Large removable resistive splitters
Equivalent to metal-cased; splitters ≥1,800 mm height
 Opening size and maintenance access
Matrix Silencers
 Impedance-composite matrix (φ3–5 mm holes)
High resistance; low-frequency pulsating gas noise
 Low-frequency noise spectrum and airflow
Acoustic Louvers
 Sound-attenuating outdoor wall opening
275.8–1,487.2 Pa loss @ 4–10 m/s (L=300 mm)
 Face velocity and outdoor boundary noise target
04 / Procurement Protocol

What Information Is Needed for Acoustic Sizing?

Essential parameters to confirm before ordering silencers or acoustic louvers.
Acoustic Sizing Checklist

Key Sizing Parameters

Submitting your octave-band fan noise data, design airflow, maximum allowable pressure drop, and dimensional space limits enables our acoustics team to size the optimal silencer configuration.

1. Fan Sound Power Level by Octave Band (63–8,000 Hz)
2. Target Room Noise Criterion (NC / NR / dBA)
3. Design Airflow (m³/h / CFM) and Duct Velocity (m/s)
4. Maximum Allowable Pressure Drop Budget (ΔP Pa)
5. Cleanliness Requirement: Standard Fibrous vs Micro-Perf
6. Available Physical Duct Dimensions (W × H × Length L mm)
7. Material: Galvanized Steel, 304/316L SS, Aluminum
8. Acoustic Louver Face Opening Sizing & Depth Basis
05 / Acoustic Verification

Octave-Band Test Data and Fabrication Quality

Acoustic silencers manufactured with CNC perforated sheet metal lines, certified glass-wool packing density, and acoustic laboratory insertion-loss verification.
Acoustic Testing

Octave-Band Verification

Insertion loss and self-generated sound power evaluated across 63 Hz to 8,000 Hz octave bands in accordance with acoustic laboratory test methods.

Media Retention

Alkali-Free Glass Cloth Wrap

Centrifugal glass-wool insulation wrapped tightly in alkali-free glass cloth behind perforated metal plates to prevent fibrous shedding under high duct velocities.

Custom Fabrication

Structural Casing Options

Custom flange drillings, heavy angle iron structural frames, and removable splitter tracks built to exact project specifications.

Disclosure: Full octave-band insertion loss and pressure loss tables are available for standard splitter and micro-perforated types. For matrix and specialized silencers, request project-specific acoustic calculation submittals.
06 / Architectural Boundaries

A Silencer Cannot Overcome an Incorrectly Sized Fan

Understanding acoustic selection trade-offs and limits.

Pressure Budget Allocation

Always add silencer dynamic resistance (8 to 120 Pa) into the fan external static pressure (ESP) calculation before ordering fans.

Fan ESP Coordination

Face Velocity Limits

Do not downsize silencers to fit tight shafts if face velocity exceeds 10–12 m/s, as self-generated air noise will ruin room acoustic targets.

Regenerated Noise Rule

Louver Face Area

Acoustic louvers have high resistance (275–1,487 Pa). Ensure sufficient wall opening area to maintain face velocities below 3–4 m/s.

Louver Area Sizing
ALERTS — NOT PART OF THE PAGE. RESOLVE BEFORE PUBLISHING.
Supplier test data is provided for standard splitters (L=1,000–1,500 mm basis), micro-perforated, and 300 mm louvers. Verify that custom silencer lengths receive scaled attenuation calculations.
Matrix silencers do not include a full octave-band insertion loss table in the source catalog; obtain project-specific test sheets before confirming contract performance guarantees.
07 / Technical Q&A

Silencers & Acoustic Louvers Frequently Asked Questions

Direct engineering answers covering splitter silencers, micro-perforated panels, pressure drops, and acoustic louver applications.

Which silencer gives the highest mid-frequency attenuation?

The Splitter Duct Silencer and Metal-Cased Splitter Silencer provide strong mid-frequency performance, achieving 35–45 dB attenuation around 1,000 Hz.

Which silencer contains no glass wool or fibers?

The Micro-Perforated Panel Silencer uses sub-millimeter perforations (<1 mm) and resonant absorption with zero fibrous filler, making it ideal for cleanrooms and humid environments.

What pressure drop should I expect from a standard splitter silencer?

YONGFAN’s tested 100 mm splitter silencer exhibits a total-pressure drop of approximately 8 Pa at 4 m/s, 35 Pa at 8 m/s, and 78 Pa at 12 m/s (ζ = 0.9).

Why do acoustic louvers have higher pressure drop?

Acoustic louvers pack sound-absorbing baffles into a shallow depth (e.g. L = 300 mm), creating higher airflow restriction (275.8 Pa at 4 m/s). Face velocity should be kept low.

What is regenerated noise?

Regenerated noise is sound created by turbulence as air rushes past silencer splitters. At high velocities (e.g. >10 m/s), generated noise can exceed 55–58 dBA, diminishing net acoustic benefit.

When should I use a Matrix Silencer?

Use Matrix Silencers for large-volume systems with low-frequency pulsating gas noise, such as engine test cells, mines, tunnels, and heavy industrial plant exhausts.

What materials are available?

Silencers and louvers are fabricated in hot-dip galvanized sheet, 304 or 316L stainless steel, or architectural aluminum.

Can silencers be built in large structural sections?

Yes. Structural Splitter Silencers utilize modular removable splitters (splitter height ≥1,800 mm, stacking height ≥400 mm) for built-up on-site acoustic banks.

08 / Application Engineering Handoff

Select an HVAC Silencer or Louver

Connect octave-band noise spectra, airflow, allowable pressure drop, and space dimensions into one confirmed acoustic schedule. Send your fan noise data to our acoustic engineers.

Splitter Duct Silencers (45 dB @ 1 kHz) Micro-Perforated (Zero Fiber · ζ=0.2) Metal-Cased Thick Splitters (200–350 mm) Structural Splitters (≥1,800 mm) Matrix Low-Frequency Silencers Acoustic Louvers (L=300 mm)
Select an Acoustic Silencer Go to Selection Center Ask an HVAC Engineer
YONGFAN acoustic engineers analyzing octave band noise spectra
Direct Acoustic Selection Support
Octave-band insertion loss analysis, pressure loss sizing, and dimensioned CAD submittals.
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