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How Kaiterra Ensures That Sensedge Devices Are Accurate and Correctly Calibrated

Christine Johnson

What makes Kaiterra air quality monitors different from the rest? It all starts with how the sensors are calibrated. Reliable air quality data starts with high-performing sensors. Without it, we know that buildings aren’t able to monitor and manage air quality effectively.

To ensure that every Kaiterra enterprise product, including the Sensedge and Sensedge Mini, can correctly track building performance and deliver an efficient and comfortable indoor environment for occupants, we set out to carefully test and verify the accuracy of the most critical part of any air quality monitoring unit—its sensors.

Almost all air quality monitors on the market are tested over just two or three levels of pollutant concentration, and only a handful of these data points are used in the calibration process. Kaiterra enterprise products, however, use over 6,000 individual measurements during the calibration and verification process.

From testing chamber design to performance certification, we created a process that verifies that every sensor is properly calibrated before and after assembly.

What Makes Our Sensor Testing Process Different?

We have designed a testing environment that goes well beyond the required industry standards. Here’s what sets Kaiterra’s sensor testing process apart:

Our custom-made testing chamber

An air-tight testing chamber is used to simultaneously test up to 360 commercial monitors over a set amount of time and in varying conditions. This custom-made testing chamber is 90 cubic meters.

Monitors are mounted on angled shelving that has been specifically designed to allow high airflow between the devices, preventing pollutant buildups from forming within the test chamber – the uniformity of the air within this chamber is extremely important. To ensure that each device is tested under consistent conditions, ventilation equipment controls the temperature and amount of the pollutant released.

Careful calibration

Certain Sensedge and Sensedge Mini sensors require calibration during the manufacturing process. For these parameters, specific concentrations of pollutants are introduced into the test chamber. This process is carried out remotely outside the test chamber so that no human interference can influence the concentration of pollutants inside.

Once the concentration of pollutant has stabilized within the chamber and is uniform throughout, all devices within the chamber will be remotely calibrated to this concentration.

Comprehensive measurement validation

Every single device that comes off of the Kaiterra production line must be fully tested for particulate matter, carbon dioxide, relative humidity, and temperature over several hours, and all readings must fall within specification. This is a hard rule; we don’t make exceptions.

While most air quality monitors on the market are tested over two or three different levels of concentration and only a handful of data points are used, the Sensedge takes over 6,000 individual measurements during the test process. Each of these measurements are processed onboard and sent to the cloud in real-time. Software in the cloud will process these readings and compare them to measured reference values within the test chamber. The divergence between the monitor’s measured readings and the reference readings are calculated for every single data point and verified against the specifications of the device. Only devices that fulfill the published technical specifications will leave the testing chamber.

Any failed devices will enter a separate process to determine where the failure occurred, and once identified, to resolve it, before returning to the production line to be fully re-tested.

A note about TVOC sensing:

Due to the chemical composition of the MOx material used in TVOC sensors, a slightly different testing process is required.

Every single TVOC sensor is individually tested and calibrated prior to assembly within the device. Following this, each sensor is soldered onto a PCB that is then assembled in the final module. The reflow soldering process creates a protective layer on the surface of the sensor’s MOx material, which helps maintain the accuracy of the sensor and prevents drift during the transportation process.

When the sensor is first used after the reflow soldering process, the surface material will experience a physical change - this is why there is an initial warm up period on the sensor. After the sensor has heated up to the required temperature, the initial protective layer is gone, and the sensor must be handled with care when it is powered off.

When powered off, the MOx material may be susceptible to interference from certain chemicals if exposed for an extended period of time. Thus, the manufacturing process ensures that the protective layer is active until the sensor is first used in the final installation location, and in the client’s hands. This method allows for the highest accuracy and lowest risk of drift in the TVOC sensors.*

To ensure that the reflow soldering process has not impacted the accuracy of the sensors, sample inspection is carried out at every stage of the production process, including a fixed percentage of fully assembled monitors. These monitors are not shipped to our clients. The data from this sample inspection is included in the Calibration & Testing report shipped with each product.

*Note that transporting the sensor after it has already been used and powered on is a risk and should be kept to a minimum. Avoid installing the modules into the device until they are installed in the final location.

Rigorous production testing

Components undergo careful production testing before and after product assembly. Electrical and sensing components are spot-checked as they enter the factory, and the entire device then goes through another comprehensive round of testing once fully assembled.

Guaranteed performance certification

Each device has a unique serial number that travels with it throughout the entire production process. This ensures that all of its components and testing measurements can be tracked and reviewed if further analysis is needed. A certification report is automatically generated for each device that has passed measurement verification. This includes select readings from the verification process, the serial number of the device, as well as other relevant data captured throughout the testing process.

All calibration and testing results are stored forever, allowing us to track any device that comes off of our production line and review all testing results (including each individual measurement) as needed.

Proper calibration and testing ensure that each Sensedge and Sensedge Mini device provides reliable, accurate readings for users to gain actionable insights needed for optimized control strategies. Using Kaiterra's commercial air quality monitors allows you to increase building efficiencies and savings, ultimately providing healthier indoor environments for your clients, tenants, and occupants.

Learn more about the Kaiterra enterprise products and find the best fit for your next building project:

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