Duct Air Leakage Test For PIR Pre-insulated Duct Systems

In HVAC systems, airtight ductwork is essential for efficient airflow, energy conservation, and long-term performance. At GFIDuct, we emphasize the importance of duct air leakage testing to verify the sealing quality of both metal and PIR Pre-insulated Duct systems. In particular, correct installation of PIR Panels plays a critical role in minimizing leakage and ensuring overall system integrity.

What is Leakage Testing?

Light Leakage Test

The light leakage test is a traditional method used to evaluate the airtightness of duct systems based on the principle that light can penetrate small openings. This test is typically conducted in a dark or low-light environment, often during nighttime, to enhance visibility.

Before testing, a 24V, 100W inspection lamp with a protective cover is prepared. During the test, one technician places the light source inside the duct and slowly moves it along the seams of the ductwork. At the same time, another technician observes from the outside to identify any light escaping through gaps or joints.

According to older ductwork standards, low-pressure duct systems are considered acceptable if the number of visible light leakage points does not exceed two per 10 meters of duct seam.

In a recent test conducted at 7:00 PM, a 13-meter duct section was inspected and found to have only one light leakage point—well within the acceptable limit. The position of the leakage point was recorded, and the test was concluded with a result of "pass."

Duct Air Leakage Test

Compared to the light leakage method, the duct air leakage test is a more advanced and quantitative approach to assess ductwork airtightness. It is commonly used for systems with higher performance requirements.

The test is performed using a duct air leakage tester, which works on the principle of injecting air into a sealed duct section and maintaining a constant internal pressure.

The amount of air required to sustain that pressure corresponds to the leakage rate.

Testing procedure:

1. Connect the outlet of the leakage tester’s fan to the duct using a flexible hose.
2. Install a pressure tap on the duct and connect it to a pressure gauge with tubing.
3. Seal all remaining duct openings to ensure a fully enclosed section.
4. Start the leakage tester and gradually increase the fan speed to raise the internal pressure.
5. Once the target pressure is reached, adjust the fan to maintain constant pressure.
6. Measure the airflow at the fan’s inlet—this value represents the duct’s leakage rate under the given pressure.
7. This method delivers accurate, reproducible results and is widely adopted in modern HVAC projects for verifying ductwork sealing quality.

Comparison: Light Leakage vs. Duct Air Leakage Testing

Light leakage inspection is a traditional method where a strong light is placed inside the duct in a dark environment to locate visible leak points. While low-cost and simple, it presents limitations:

• Highly subjective and reliant on visual detection.
• No control over leak area size.
• Dependent on dark surroundings, limiting use to night-time or low-light conditions.

In contrast, duct air leakage testing is:

• Quantitative and reproducible.
• Capable of detecting invisible or hidden leaks.
• Aligned with modern HVAC industry standards.

PIR Pre-insulated Duct Installation and Leakage Risk

PIR Pre-insulated Duct products are valued for their high thermal resistance, lightweight design, and rapid installation. However, improper handling or assembly can lead to unintended air leakage. Key installation points include:

Joint Sealing:

• All panel joints should be tightly sealed with approved aluminum tape and sealant to prevent leakage.

Flange and Connector Alignment:

• Misaligned flanges or poorly secured connectors can create gaps, reducing the effectiveness of the PIR Panels.

Accurate Cutting and Handling:

• Over compressed or uneven cuts may damage the foam structure, resulting in air escape points.

Post-Installation Testing:

• After installing PIR Pre-insulated Duct, it's crucial to conduct duct air leakage testing to ensure airtightness is maintained throughout the system.

خاتمة

Whether using traditional sheet metal ducts or advanced PIR Pre-insulated Duct systems, airtightness is the foundation of HVAC performance. At GFIDuct, we combine high-quality PIR Panels with expert installation and rigorous duct air leakage testing to deliver energy-efficient, reliable ductwork for commercial, industrial, and cleanroom applications.

Investing in proper installation and scientific testing ensures optimal airflow, reduced energy loss, and enhanced indoor comfort.