AHU Ducting & Terminal Connection Setup: Acoustic Sound-Attenuated Ducting

In the 2026 Malaysian engineering landscape, Acoustic Sound-Attenuated Ducting is a technical necessity for Grade-A offices, healthcare facilities, and recording studios. As AHUs become more powerful to meet EECA 2024 airflow requirements, managing the "Regenerated Noise" from high-velocity air and the "Break-out Noise" from the fan motor is critical for achieving NC 30-35 acoustic ratings.

At EKG (Malaysia) SDN BHD, we engineer sound-attenuated setups to be Sterile, Silent, and Statutory-Compliant, ensuring your facility meets the comfort standards of MS 1525:2024.

1. The Engineering Components of Acoustic Ducting

A silent ducting setup utilizes a multi-layered approach to absorb sound energy before it reaches the terminal outlet.

• Duct Silencers (Sound Attenuators): These are "muffler" sections installed in the main supply and return ducts. They contain internal baffles or "splitters" filled with acoustic media (typically mineral wool with a glass-cloth facing to prevent fiber erosion).

• Acoustic Lining (Internal Lagging): The interior of the duct is lined with 25mm or 50mm of acoustic insulation. This is particularly effective for absorbing high-frequency "hiss" from VFD-driven fans.

• Acoustic Lagging (External Wrapping): For ducts passing over noise-sensitive areas, heavy-density mineral wool with a loaded vinyl barrier is wrapped outside the duct to prevent "Break-out Noise" from leaking into the ceiling void.

2. Statutory Acoustic Standards: MS 1525:2024

The updated Malaysian standards provide strict Noise Criteria (NC) levels for different indoor environments. Failure to meet these can lead to occupant dissatisfaction and building audit failures.

3. The VFD & Acoustic Relationship

The use of Variable Frequency Drives (VFDs) adds a unique acoustic challenge: Magnetic Hum.

1. Carrier Frequency Tuning: At EKG (Malaysia) SDN BHD, our engineers tune the VFD's switching frequency (typically between 8kHz and 16kHz) to shift motor noise out of the human audible range, ensuring the AHU remains "Silent."

2. Resonance Avoidance: We utilize "Skip Frequencies" in the VFD programming to bypass specific RPMs where the ductwork might vibrate or "rumble" due to mechanical resonance.

3. Low-Velocity Design: To maintain a low SFP (Specific Fan Power) while remaining quiet, we size attenuated ducts for a velocity of 4.0 to 6.0 m/s, preventing the generation of air turbulence noise.

4. The "Fire Mode" Statutory Protocol

Acoustic materials must not compromise the building's fire integrity. Under BOMBA (JBPM) 2026 regulations:

• Non-Combustible Media: All acoustic linings and silencer fill must be Class 0 (non-combustible) and low-smoke emitting.

• Fire Damper Placement: Acoustic silencers must be installed after the fire damper or be fire-rated themselves if they penetrate a compartment wall.

• FAMS Integration: Upon a fire signal, the VFD shuts down the AHU, and the fire dampers close. The acoustic setup must be robust enough to withstand the sudden pressure change without internal baffles collapsing.

5. Why Partner with EKG (Malaysia) SDN BHD?

• Technical Integrity: Our acoustic designs are verified using Sound Power Level (Lw) calculations for the specific AHU fan selected, ensuring the NC target is hit mathematically, not by guesswork.

• Sterile-Grade Solutions: We specify "Melinex" or "Tedlar" facings for acoustic media in cleanrooms and hospitals to prevent fiber shedding while maintaining sound absorption.

• EECA Compliance Support: We ensure that the added pressure drop from silencers is accounted for in the Specific Fan Power (SFP) calculation, keeping you within the statutory 1.6 kW/m³/s limit.

Is your AHU causing distracting noise or "duct rumble" in your facility? Contact EKG (Malaysia) SDN BHD today for a specialized Acoustic Sound & Vibration Audit.