Air Quality Sensor

[ysinh]

@tuimanso
There seems a general misunderstanding about how those gas sensors really work: the "heater" must be switched on (5v) and "off"(1.4v) for the air sample going in and out of the sensor, when heating the air sample expands and goes out of the sensor, then in the cool down period the remaining air contracts and sucks in a new sample.
Those boards with mq... sensors only provide fixed 5v heating, so this can never work reliable
the 1.4v is needed to keep the sensor on a minimum temperature,example 40'c for the catalyst to react, the 5v will heat it up to example 80'c, to clean the catalyst and air flows out of the sensor
http://i49.tinypic.com/2rzdqgn.png something like this will work
Soon I will report my results together with a modified sketch for mysensors 2.0

[bezeefly]

@epierre I am working on a dust sensor project using Samyoung DSM501A. I am confused with the identical calculation formula used in the Samyoung DSM501A and Shinyei PPD42NS dust sketch.

concentration = 1.1pow(ratio,3)-3.8pow(ratio,2)+520*ratio+0.62;

My understanding is that the formula is based on the specific product's data sheet curve. Is the formula for DSM501A, PPD42NS, or both?

[epierre]

@bezeefly said:

Samyoung DSM501A and Shinyei PPD42NS

This is formula for Shinyei, you're right, I'searched back but don't know if a formula was made out : https://groups.google.com/forum/#!topic/airqualityegg/A1F9padoW10

strangely here it is used too : http://learn.linksprite.com/arduino/shields/use-dust-sensor-dsm501-with-arduino/

a formula by Chris Nafis here: https://github.com/OSBSS/Samyoung_Dust_Sensor/blob/master/Samyoung_Dust_Sensor.ino

[bezeefly]

@epierre I obtained the following equation by polynomial fit the low ratio vs particle (pcs/283ml) graph in the DSM501 datasheet.

concentration = (0.1 * pow(ratio, 2)) + (619 * ratio) + 50;

Please help to check whether the equation is correct.

[epierre]

@bezeefly said:

@epierre I obtained the following equation by polynomial fit the low ratio vs particle (pcs/283ml) graph in the DSM501 datasheet.

concentration = (0.1 * pow(ratio, 2)) + (619 * ratio) + 50;

Please help to check whether the equation is correct.

looks correct for the red curve

using http://www.xuru.org/rt/PR.asp with:
4 2500
8 5000
12 7500
16 10000
20 12500
22 15000
gives =7,613212955POWER(B3;2) + 467,3617082B3 + 631,9862425

a bit better ;-)

and on the previous one datasheet http://www.mouser.com/ds/2/744/Seeed_101020012-838657.pdf:
2 1000
3.9 2000
5.8 3000
7.2 4000
9 5000
10 6000
11.3 7000
12.6 8000
y = 19.09464953 x2 + 383.1041412 x + 174.9189116

[jumping]

Hello,
I bought the classic MQ sensors (MQ2, MQ4 and MQ135) and I'm building a multisensor node with arduino nano v3:
@epierre can I use sketch https://github.com/empierre/arduino/blob/master/AirQuality-Multiple_Gas_Sensor1_4.ino, is it suitable?
thanks

[epierre]

@jumping you will need to scale down the script obviously, in term of power it will be too short to have more than one.

[jumping]

@epierre said:

@jumping you will need to scale down the script obviously, in term of power it will be too short to have more than one.

thanks for your answer! please, can you explain how the following code in your sketch is related to datasheet?

• float CO_secCurve[2] = {726.7809737, -4.040111669}; //MQ135

I understand the sketch in the "Gas Detection - Example", but not the previous.
sorry for my poor english :-)

[epierre]

@jumping see just above on power regressin curves, this is the result from a power regression based on the data sheet provided by one maker. Sometime I leave the data points in the sketch, sometime not (based on history ;-)

[ambuj]

@epierre Hi I am working on the MQ2 sensor, I want to know CO level. Did you do it before with this sensor?

http://www.amazon.in/Butane-Hydrogen-Sensor-Detector-Arduino/dp/B01N0XSQ9J?tag=googinhydr18418-21&tag=googinkenshoo-21&ascsubtag=9d5b3107-037a-4d7b-a8b9-722d0a4bcfea.

I am using this module and just start work with this sensor.

[Lukács Attila]

@epierre is it possible that the lastest github for Samyoung 501a is not correct? Flashed it and the results are way too high (157000 mg/m3)?

[surepic]

Ppm percentage calculations in the code seems wrong. Instead of providing rs/ro ratio to the function is transfered rs value not the ratio.

[epierre]

@ambuj please see the begining of the discussion regarding MQ like reliability

[epierre]

@lukács-attila check wiring first, seems there are several sub version around thay may need other values from datasheet

[alexsh1]

@surepic Which sensor? Which code? Would you please be more specific?

[Rosmel]

@alexsh1
Hello, I am working recently with tgs8100 sensors, and I am developing a project, I would like to know how it was in the results? How did you acquire them? Any arduino code? Thank you

[alowhum]

@rosmel said in Air Quality Sensor:

tgs8100

That's also quite a non-precise sensor if I understand correctly. Useful for general 'how's the air', but because it will respond to so many different 'polutants' you never know which of those polutant is the culprit.

You will find code in the forum for good CO, CO2 and fine dust sensors.

[rayzyzy]

Hi,
Working with tgs2602 , tgs 2620 and tgs2611 . I've read the replies from top to bottom but haven't understood how
exactly i take data from the graph in datasheet and use it with power regression .