In HVAC systems, ducts not only transport air but also serve as crucial channels for noise transmission. Improper control of fan noise and airflow noise directly impacts the acoustic quality of the building's interior. Fiberglass ducts, due to their unique material structure, offer both thermal insulation and sound insulation, making them widely used in buildings with high acoustic requirements. This article will systematically analyze the sound insulation and noise reduction performance of fiberglass ducts and its underlying principles.

I. Main Sources of Noise in HVAC Systems

Before understanding the noise reduction performance of fiberglass ducts, it's necessary to identify the main sources of noise in the duct system, including:

1. Fan operating noise

2. Aerodynamic noise generated by high-speed airflow within the duct

3. Structural sound transmission caused by duct wall vibration

4. Noise propagation along the duct into the indoor space

The acoustic properties of the duct material directly affect noise control.

II. Material and Structural Characteristics of Fiberglass Ducts

Fiberglass ducts typically use fiberglass insulation boards as the main material, which are cut and spliced to form duct components. Their structure has the following characteristics:

A porous fiber structure inside

The material itself has a certain thickness

The duct wall possesses both rigidity and sound absorption properties

Different functional coverings can be applied to the inner and outer surfaces

This structure gives fiberglass ducts a natural advantage in acoustic performance.

III. Basic Principles of Sound Insulation and Noise Reduction in Fiberglass Ducts

The sound insulation and noise reduction performance of fiberglass ducts is mainly achieved through the following acoustic mechanisms:

Sound energy absorption

Sound wave attenuation

Vibration suppression

Noise propagation path weakening

These multiple mechanisms work together to effectively reduce noise levels in duct systems.

IV. Sound Absorption Mechanism of Porous Fiber Structures

1. Sound waves are consumed when entering the fiber pores

The interior of a fiberglass duct consists of a porous structure formed by numerous interwoven glass fibers. When sound waves enter these pores:

Air molecules vibrate repeatedly within the pores.

Sound energy is converted into minute amounts of heat energy due to friction.

The sound wave intensity gradually attenuates.

This process is the core mechanism by which fiberglass ducts achieve sound absorption and noise reduction.

2. Significant Absorption of Mid-to-High Frequency Noise

Fiberglass materials have good absorption capabilities for mid-to-high frequency noise, which is one of the most common types of noise in air conditioning systems.

V. The Attenuating Effect of Duct Wall Structure on Noise Propagation

1. Built-in Sound-Absorbing Layer in the Duct Wall

Compared to metal ducts, the duct wall of a fiberglass duct is itself a sound-absorbing material. Sound waves are continuously attenuated during propagation within the duct, rather than being amplified by reflection.

2. Reduced "Duct-Transmission" Effect

Fiberglass ducts effectively reduce the problem of noise propagating over long distances along the duct, causing noise to gradually attenuate during transmission.

VI. Suppression of Structural Vibration and Noise

Metal ducts are prone to resonance and vibration noise during operation due to airflow impact. Fiberglass ducts, however, due to:

higher internal structural flexibility

superior damping performance compared to metal materials

can suppress duct wall vibration to a certain extent, thereby reducing structural sound transmission.

VII. Performance of Fiberglass Duct Sound Insulation and Noise Reduction in Practical Applications

1. Office and Commercial Buildings

In office buildings, shopping malls, and other places with high comfort requirements, fiberglass ducts help reduce background noise and improve the user experience.

2. Hospital and Educational Buildings

In hospitals, schools, and other buildings requiring a quiet environment, the sound absorption characteristics of fiberglass ducts can help improve the indoor acoustic environment.

3. Machine Rooms and Equipment Areas

In areas with concentrated noise sources, such as fan rooms and equipment rooms, fiberglass ducts can serve as an important component of system noise reduction.

In summary, the sound insulation and noise reduction performance of fiberglass ducts mainly stems from the sound energy absorption capacity of their porous fiberglass structure, as well as the suppression of noise propagation and vibration by the duct wall structure. The appropriate application of fiberglass ducts in HVAC systems helps to improve the overall acoustic environment quality while meeting air supply requirements.