------Question for ENS160-BGLM Please Put your question below------
I hope this message finds you well.
We are currently developing an air quality monitoring device using the ENS160 sensor, and we would like to better understand how the TVOC output is defined and interpreted.
In particular, we would appreciate your clarification on the following points:
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Reference Gas for TVOC Output
Could you please clarify which reference gas (e.g., ethanol, toluene, isobutylene, etc.) is used internally for the TVOC calculation?
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Conversion Method
Is there a recommended method to convert the TVOC output (ppb) into a mass concentration (e.g., mg/m³)?
If so, could you provide any reference formula or guidelines?
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Interpretation of TVOC Values
Should the TVOC value be considered as a specific gas concentration equivalent, or rather as an aggregated index of multiple VOC gases?
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Comparison with Other Instruments
When comparing ENS160 TVOC values with other measurement devices that report mg/m³, what would be the recommended approach to ensure meaningful comparison?
We would greatly appreciate any technical documents or application notes you could share regarding this topic.
Thank you very much for your support.
Greetings,
It may be preferable to contact the manufacturer directly in relation to such questions, since those folks will have more immediate familiarity with the product and subject matter than those of us who also support several million additional products. The supplier’s documentation page may also contain some items of interest.
That said, my best guesses at responding to your questions follow.
1 ) Page 8 of the datasheet appears to suggest that the reference gas is likely a standardized mix intended to be representative of that found in typical application conditions. Specifics beyond that are a thing I’ve not been able to zero in on after a some searching.
2 ) Assuming that the ppb figures are reported on a molar concentration basis, conversion to a mass basis would seem to involve accounting for the varying densities and proportions of the component gasses in the reference mix. It may be a bad assumption to make though, and getting an answer to the first question would probably be needful to make progress on the point.
3 ) Recognizing that the sensor itself has broad cross-sensitivities and that it’d be unusual for an application to encounter any specific chemical species in isolation while afield, I’d interpret the TVOC values reported as something closer to a synthetic index figure than an actual analytical result. Could a person back out equivalent values for single-gas responses in lab tests? Probably. But at days’ end here we’re talking about a $5 sensor targeting ventilation control applications having maybe 2 to 3 bits’ worth of meaningful resolution, not a $50K gas chromatograph.
4 ) Much would seem to depend on exactly what those other instruments are reporting. Assuming that we’re talking about devices of a similar class and purpose, it would seem likely that those other devices are reporting something like a synthetic index figure as well, making the whole comparison issue somewhat fuzzy. And again, for applications that really only need to divide the spectrum between springtime freshness and gag reflex activation into maybe 5 or 6 discrete steps, the precise analytical demarcations between those bins probably isn’t all that important, as long as the answers given from one instrument to another are in the same ballpark.
