Formaldehyde WP6930S vs uRAD A3

Formaldehyde CH2O is a very dangerous chemical-gas that can be easily found inside a house because it off-gases from paints, carpets, furniture, etc… In this article I am going to find out how well a cheap, handheld air quality monitor WP6930S compares to a more professional solution such as the uRAD A3.

It wasn’t an easy task because the WP6930S doesn’t permit you to transfer the log file to the computer and finally I had to convert the measurements I took from the A3 because it measures in ppb and the WP6930S in mg/m3. It also took time to collect data because there wasn’t enough pollutant to measure throughout the days.

The Formaldehyde has a Molar mass of 30.031g/mol which allowed me to convert correctly all the values from ppb to mg/m3.

The A3 was already pre-calibrated but the WP6930S wasn’t so when the A3 had zero readings the WP6930S was able to detect something falsely. Remember the latter allows to adjust with a slider the measurements to match other devices by % percentage or ± value.

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All the measurements were taken randomly during a whole week. The final value of R2, the coefficient of determination, is 0.6639. I think If I had calibrated the WP6930S I would have achieved a better R2 result. Just because this device had these results it doesn’t mean all the WP6930S will have the same ones, remember they don’t come pre-calibrated but they can be calibrated later by the user if they have the tools to compare the measurements.


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