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MG811 CO2 gas sensor and 27929 parallax module temp and hum dependency — Parallax Forums

MG811 CO2 gas sensor and 27929 parallax module temp and hum dependency

mizzardmizzard Posts: 5
edited 2012-04-13 04:04 in Accessories
Hello everybody, I am doing my first test with MG811 sensor and 27929 parallax module.
First of all, I am trying to understand the Hanwei datasheet but I have some questions related with Temperature and Humidity dependence.
  • In specifications table we can see that EMF output varies from 30-50 mV that means 350-10000 ppm CO2, but in the following figures we can see variations of EMF from 250 to 360 mV. Is the specification table wrong?
  • From figure 2 we can see aprox 325 mV for 350 ppm CO2 where environment conditions are temp 28 ºC, 65% RH and Oxygen 21%. If we see humidity table, for the same humidity and ppm (aprox 65%RH and 350 ppm CO2) we can see aprox 350 mV. What about temperature?
  • If we see temperature dependency table for 65% RH and approx 28ºC and 350 ppm we can see 340 mV more or less.
  • After that, how should I understand these information to make adjustements for variations of temperature and humidity? These few variations of mV means a lot of variation of ppm. Buying these sensors implies to buy another professional with LCD to calibrate each one simulating every condition of temperature and humidity?
I hope some additional information to clear my doubts because I am very interesting in calculate approx ppm CO2 for different conditions of humidity and temperature.

Thank you so much
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