I have a project where i need to measure the ppm of various gases.
I'm pretty new to the arduino gas sensors world, i purchased the mq-series and then i noticed that is not what i need: the mq-series does not measure the ppm of single gases, but they only detect if there is an increse of concentration. Also i need to measure ppm of single gases, for example if i need to measure the carbon monoxide, i can't because the MQ-7 is sensible to other gases also.
If you guys can recommend me some sensors that actually measures the ppm of SINGLE gases, with a medium price range, would be great!
Some of the gases that i need to measuse: CO, CO2, O3, SO2, H2S, N2O
Thanks in advance!
Edit:
We are sending a sounding baloon in the stratosphere, and the idea is to also put inside the box a sort of on-board computer with arduino that collects data about pollution from the ground, all the way to the space.
Sincerely, i have no idea what ppm range i need for each gas (if you have an advice, it would be beautiful).
It must not be very precise, but the data must be reliable.
We have sent multiple balloons into space in the past, and we retrived all of them succesfully thanks to a gps device.
Hi,
Welcome to the forum.
I think you will need to look at industrial or medical grade sensors to measure actual levels.
What sort of resolution do you need.
The general rule is the higher the resolution required, exponentially the cost increases.
What range of ppm do you want to measure each gas?
What is your project that needs this sort of precision?
TomGeorge:
Hi,
Welcome to the forum.
I think you will need to look at industrial or medical grade sensors to measure actual levels.
What sort of resolution do you need.
The general rule is the higher the resolution required, exponentially the cost increases.
What range of ppm do you want to measure each gas?
What is your project that needs this sort of precision?
Tom...
Hi Tom,
Thanks!
So, we are sending a sounding baloon in the stratosphere, and the idea was to also put inside the box a sort of on-board computer with arduino that collects data about pollution from the ground, all the way to the space.
Sincerely, i have no idea what ppm range i need for each gas (if you have an advice, it would be beautiful).
It must not be very precise, but the data must be reliable.
Hi,
It looks like some more research is needed.
Have you sent a sounding balloon up before?
You need to consider the low temperatures involved and battery and sensor performance.
As you are going up into low pressure atmosphere, concentrations will probably be very low if you are looking at ppm.
This is out of my field unfortunately.
Can I suggest you change the subject of this thread to include high altitude balloon in it, that way you will probably get a more informative response.
You as the thread originator can edit the thread subject.
Try something like;
Gas concentration measurements in high altitude balloon project.
At the moment your subject infers a Gas Meter that to most people is the gas meter you have attached to your home for gas supply.
Also consider the power requirements for the sensor. And the design of your payload. The sensors have to have a continuous flow of OUTSIDE air. You cannot hide the sensor inside some enclosure.
Paul
Sorry, can't give specific suggestions for sensors, but I can give you my thoughts on how I would approach a project like this from an engineering perspective.
Start with more research: find out what ppm you can expect. No doubt for your location others have done similar projects, maybe your government is monitoring regularly. Likely the highest concentrations are on the ground level (where most pollutants are produced), if you go high enough you may find a bit more ozone (in the ozone layer). This tells you what sensitivity range your sensors need. When you have that, you can consider resolution; of course the higher the resolution and accuracy of your sensors the more they will cost.
Sensors are going to be expensive indeed, so you will want to make really sure that you can recover them in one piece. Experience with high altitude balloons and recovery of your payload becomes important. An Arduino may well survive a crash landing when packed properly (making just the SD card with your data survive is even easier to accomplish), the sensitive gas sensors not so much. Then there's also the issue of physically finding and retrieving whatever parts have come back down.
You may be able to borrow sensors from a local government or environmental organisation, but both are likely to ask you for a track record on safe recovery, so they can be pretty sure to get back their expensive equipment in working order.
When that is all set, there's indeed the issue of putting it all together into a working project...
alessandro_place:
Guys, first of all, thanks to all of you for trying to help us!
I edited the topic with more details.
Now i'm gonna do some research and update with some information.
In the meantime, if someone knows some brands of sensors that could fit well with this project, let me know!
You are searching for sensors that give ppm values. Such sensors, if calibrated at all, will give numbers based on the standard pressure and temperature at seal level. If not being used at the standard, the value given will NOT BE TRUE for your location. Especially since the location is gaining altitude very rapidly.
The result is you must calculate the current PPM adjustment based on the sensor reading, the current air pressure and the current air temperature. No meter will do that for you.
Good luck.
Paul
