units of measurement

[Bettina Rubin de Souza]

I have a doubt about the units of measurement, I want to compare the air quality egg data with acceptable levels of each pollutant according to the laws of my country.
here we measured in ug / m3 and the AQE in ppb.
what is ppb for you? how can i transformate ug / m3 for ppb?

[Victor Aprea]

Which type of Egg do you have?
NO2, O3, and SO2 are reports in ppb
CO is reported in ppm
Particulate is reported in ug/m^3

I haven't vetted it, but this site looks like a pretty good online converter.

http://hiq.linde-gas.com/en/specialty_gases/gas_concentration_units_converter.html

Kind Regards,
Vic

I have a doubt about the units of measurement, I want to compare the air quality egg data with acceptable levels of each pollutant according to the laws of my country.
here we measured in ug / m3 and the AQE in ppb.
what is ppb for you? how can i transformate ug / m3 for ppb?

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[Bettina Rubin de Souza]

My Egg is the version 2 No2 CO..
the questions is, ppb can be, volume/volume, weight/weight, volume/weight
usually is volume/volume..
so, does the air quality egg considers ppb volume/volume?

[Victor Aprea]

Bettina, 

Good question. "ppb" indicates "ppbv", or ppb by volume

Kind Regards,

VIc

Victor Aprea // Wicked Device

victor...@wickeddevice.com

T: @vicatcu

[Bettina Rubin de Souza]

thanks a lot! that information will be very useful..
i've got a couple more questions:
1) Why the data doesnt have cietific value? is that because of the calibration?
2) Is the equipment (AQE)calibrated individually? or is a generic calibration with error margin?
3) How much energy the AQE spends in kwh?

[Victor Aprea]

Bettina,

1) Why the data doesn't have cietific value? is that because of the calibration?

I don't understand what cietific means (and Google isn't helping). My best interpolation is that you meant "scientific", and if that's what you meant, I simply would disagree with the statement. Version 2 Egg sensors are factory calibrated by the manufacturer (for span) and zeroed in circuit by us, and we attempt to compensate for significant secondary effects like those due to temperature in software as well. (* more on this below)

For what it's worth, I would say that Version 1 was much less of a "scientific instrument" (whatever that means) than Version 2, but I would not go so far as to say Version 1 had "no scientific value." Accuracy and precision are important, but at some level there's much more to Air Quality Egg than numbers.

 

2) Is the equipment (AQE)calibrated individually? or is a generic calibration with error margin?

Yes each Version 2 Air Quality Egg is calibrated individually (both for span and for zero). Our temperature compensation currently is "generic" based on typical characteristics published in the datasheets for our sensors. Individualizing the temperature compensation is something we've been kicking around as an idea to further improve the accuracy of our measurements. We always have to consider the tension between the price to manufacture the product and the accuracy that we can practically achieve. Measuring ambient levels of gases is generally acknowledged to be a pretty hard problem fundamentally.

 

3) How much energy the AQE spends in kwh?

This is based on my memory and I haven't measured it lately, so treat this like a ballpark esitmate, but Eggs draw between 100mA @ 5V and 300mA @ 5V. That's between 0.5W and 1.5W. So, back of the envelope, it would take between 675 and 2000 hours for an Egg to burn a kW. Where you fall in that range depends on hardware options and how you operate the Egg. 

There are currently three Models of Sensor Packages (NO2/CO, O3/SO2, Particulate) and each can be configured for two operating modes (Online, Offline), and any Egg supports optional hardware elements (GPS, RTC, SD card). Of course each combination has different power consumption characteristics. The standard configuration (Online mode, no GPS, no SD card, no RTC) draws about 220mA @ 5V. The Offline + SD + RTC configuration draws about 110mA @ 5V.

Hope that helps!

Kind Regards,

Vic