Imagine you are the facilities manager at the manufacturing plant shown in the photo below left, and you’ve been told there’s a leak in one of those pipes moving air or another gas under pressure. How do you find the leak?

At a cost of about $21,000, plant managers can use an acoustical imaging device made by Flir (right) to detect leaks in compressed air, gas, or vacuum piping systems.
At a cost of about $21,000, plant managers can use an acoustical imaging device made by Flir (right) to detect leaks in compressed air, gas, or vacuum piping systems.
This technology is now being harnessed to detect building enclosure leaks and fortunately is available for vastly lower costs.
This technology is now being harnessed to detect building enclosure leaks and fortunately is available for vastly lower costs.

Until recently, the process might have taken a lot of time and effort manually checking each pipe and joint individually. Lucky for us, a tool has been developed that speeds things up; it uses “acoustic imaging”—think thermal imaging, but instead of seeing temperature differentials, the device “sees” sound. Several manufacturers are currently producing this test equipment.

Now imagine this technology being developed for the residential construction industry. Instead of using sound to detect leaks in pipes, we use the equipment to find air leaks in the building enclosure. We are already performing this type of testing using pressure differentials with a blower door test. Testing for air leaks using sound is an up-and-coming technology; it won’t replace the blower door test, but it could help practitioners speed testing.

Limits of Blower Door Testing

Blower door testing in residential construction has been around since the 1980s but didn’t gain a good foothold in the industry until the 2000s. A blower door uses a fan to create a pressure differential inside the building. We’ve learned that by measuring pressure differentials and the fan speed and knowing the size of the opening (the ring size or range plug, depending on the fan’s manufacturer) in the fan that the air is moving through, we can calculate total building leakage rates. We can also use the fan to locate the air leaks in the enclosure.

There are a few methods to find air leaks: Theatrical smoke, thermal imaging, or simply feeling for air movement with your hand can be effective. But there are some limitations to using pressurization for detecting air leakage in building enclosures and assemblies. For one, you need to be able to create a pressure differential. If the air barrier is not complete, creating the needed pressure difference between inside and out for a successful test is difficult.

Other challenges exist, too. Blower door testing can be disruptive to the schedule; often, trades are stuck inside or outside while testing occurs or need to be kept off site on testing days. Setting up the blower door to test one assembly, such as a window or door installation, takes time. Using thermal imaging while blower door testing requires a temperature difference between inside and out to be effective, and that difference doesn’t always exist during a test.

Acoustical Leak Detection

Acoustical leak detection, which uses sound to find air leaks, isn’t new technology. It has been used for decades on ships to test hatches for watertight integrity. During COVID, Coltraco, a British company, built a device based on that watertight-hatch technology and called it a Portascanner COVID-19. The tool was used to test airtight assemblies in the medical field. It wasn’t a big leap for that device to make its way into the construction industry.

Coltraco’s equipment has two main parts—a sound generator and a microphone/wand connected to a digital receiver. There are two versions of the tool, Portascanner and Portascanner Airtight. The standard Portascanner (the model I own) simply identifies the leak location and supplies a basic reading as to the leak’s intensity.

Coltraco’s Portascanner consists of a sound generator and a microphone wand connected to a digital receiver. This model identifies the leak location and supplies a basic reading as to the leak’s intensity.
Coltraco’s Portascanner consists of a sound generator and a microphone wand connected to a digital receiver. This model identifies the leak location and supplies a basic reading as to the leak’s intensity.

The more advanced Portascanner Airtight can also quantify the leak by providing calculated airflow rates. The Airtight’s digital readout features a touchscreen camera for taking digital photos on which the device can plot leak locations. After testing is complete, a report can be generated which will include a photo of the area tested, showing the air leak locations and the leakage rates.

The ability of the Portascanner Airtight to calculate the leakage rate of a hole in a building enclosure is unique. There are methods to calculate individual air-leakage rates within a building enclosure using a blower door, but it’s not easy. For instance, I’ve used a powered flow hood during a blower door test to estimate the CFM50 leakage rate for recessed light fixtures and could probably do the same for other building assemblies, but it takes some work to isolate the leak from the rest of the building.

I had the opportunity to demo the Portascanner Airtight at a recent builder’s show. I didn’t have enough time working with the tool to fully appreciate all its capabilities, but I saw enough to understand how the equipment can be useful. Based on that experience, I decided to purchase the standard Portascanner.

The author has begun using the Coltraco Portascanner, which the manufacturer has dubbed an “ultrasonic room integrity testing tool,” to find specific building enclosure leaks.
The author has begun using the Coltraco Portascanner, which the manufacturer has dubbed an “ultrasonic room integrity testing tool,” to find specific building enclosure leaks.

Using the Portascanner

Using the more basic Portascanner is simple: You set up the sound generator, assemble the microphone/wand to the extension poles and handle, connect the microphone/wand to the receiver, plug in the headphones, and you are ready to go.

The generator produces sound at a frequency of 40kHz, well above what humans can hear. I did notice that my cats react to that frequency; the noise didn’t hurt them, but they heard it. The instructions suggest placing the generator about 15 feet from the area being tested, on the opposite side of the building assembly from the microphone/wand. The microphone/wand is then moved slowly along the area being tested. When it encounters an air leak, the digital receiver produces a sound through the headphones and shows a reading on the display as either a decibel scale or a linear scale that informs the user of the leak.

When a leak is detected, the sound will become louder in the headphones and the reading on the display will show the leak’s intensity. The decibel scale ranges from 0 to 75 and the linear scale, from 0 to 31,775. A reading of 0 on either scale means the assembly being tested is airtight. Higher readings indicate air leaking through the assembly. The manufacturer claims that leaks as small as 0.06mm—about half the diameter of human hair—can be detected with the equipment. That is a very small building leak.

The equipment is simple to use and intuitive for identifying leak locations, though I am looking forward to using and testing the equipment to better understand leakage rates and their relationship to the scales used by the equipment. The model I own cannot estimate the actual leakage rate, but gaining experience with the equipment should help me differentiate between a leak that requires sealing and one that’s not worth the time and effort.

Moving Forward

Earlier in this article, I mentioned the use of acoustic imaging cameras to identify air leaks in compressed air, gas, or vacuum piping systems. The ease of simply pointing a camera in the direction of a potential leak point and identifying its location is current technology. Though it’s not commonly used to detect leaks in building enclosures, the technology is heading there, in my opinion. The Airtight model currently available already includes a touchscreen camera, and I imagine this will become more central to the operation of the tool. Hopefully, the cost of this technology will become more accessible to the building trades as the technology advances and more of these tools become available. Again, it’s not a replacement for blower door testing but an additional tool that can help our buildings become better.

The standard Portascanner retails for about $4,000; the Portascanner Airtight, $12,000. Both tools are available in North America only through Source2050 (source2050.com/coltraco/). More information can be found on the Coltraco website (coltraco.com).