The molar mass of carbon monoxide (CO) is 28.0, and the molar mass of air is 28.8, so CO will rise in an ambient atmosphere. It makes sense to detect it farther from the ground, but getting a tall ladder is not convenient and certainly doesn’t make for fast deployment. What do you do if you don’t care for heights and want to know the CO levels in a gymnasium or a tall foyer? Here to save the day, is the Red Balloon Carbon Monoxide Detector.
Circuit.io generates the diagram and code to operate the CO sensor and turn a healthy green light to a warning red if unsafe levels are detected. The user holds the batteries, Arduino, and light while a red balloon lifts the sensor up to fifteen feet, or approximately five three meters. It is an analog sensor which needs some time to warm up so it pays to be warned about that wire length and startup.
Having a CO sentinel is a wise choice for this odorless gas.
Thank you [anatza] for the tip.
Those cheap (chinese) sensors look interesting, but how do you calibrate them? I don’t want to mess with CO. There are precalibrated modules with digital IO avaible but they are quite expensive.
>>but how do you calibrate them?
You don’t. Most of them were calibrated at the factory using pure nitrogen and then self calibrate on powerup. You could do that if you had a way to read the sensor and a high purity nitrogen tank, but those are a bit more expensive than the normal tanks at the welding supply shop. So as long as you don’t turn them on near the tail pipe of a running car they calibrate to normal background CO concentration. Which is apparently just shy of 400ppm.
The 400ppm figure is CO2.
CO in the atmosphere is around 80ppb (per billion), less than 1/1000 the concentration cited.
(Assuming you’re on Earth, of course. Can you see the sun from where you are?)
400 PPM of CO would be potentially life threatening after around 3 hours.
I thought that sounded high. That’ll teach me too trust the first link I click on
Are you sure these cheap sensors from China are correctly calibrated and/or have self calibration? They are avaible for less than 2$, i somewhat doubt the quality… https://www.aliexpress.com/item/1Pcs-New-MQ-7-MQ7-Carbon-Monoxide-CO-Gas-Sensor-Detection-Module-For-Arduino-Free-Shipping/32826969192.html
Maybe i should buy 2 or 3 and compare the results…
@some guy What does “quite expensive” mean to you ?
I don’t remember the exact prices but these modules cost far more than a commercial warning device (i paid mine 35€ iirc) or i was not even able to find a price online for 1 piece. YMMV
Calibrated gas is available for example at
https://logidatatech.com/de/produkte/wartung/kalibriergase/kohlenmonoxid
Yes, you can buy such things (can you if you are not a company?), but you need some tight chamber and good ventilation to calibrate your sensors safely. CO ist dangerous, i don’t want to mess with it.
A good educational experience but I’d rely on a commercial CO detector for safety. I’m more interested in CO levels where I breath, not up in the air.
“15 feet… approximately 3 metres”
Yah, just round that last 1.572 metres down, she’ll be right.
Yup, I messed up the math. Thank you for catching that.
Just use the sane system of measurements from the beginning and that won’t happen ;)
Seriously, as a person raised in the US–the decision to learn and intuitively think in metric despite my environment has definitely paid off. Especially for people who have a habit of designing and building things. It’s so, so much better. You don’t really see it until you’ve done a few projects entirely in metric and notice the absence of all the little headaches that we usually take for granted as an unavoidable part of work. It’s totally avoidable.
When I was in college, I thought I would get to the real world of industrial engineering and metric would reign supreme with a few pockets clinging to inches and Fahrenheit. It turned out that the opposite was true. I can count on one hand all the metric-based l projects I have been a part of.
I would still like to see this change.
I had a teacher say that 2 is a “ballpark figure” for pi.
B^)
Anyone else with 99 Red Balloons stuck in their head now?
I have had it stuck in my head for a couple of days now. I’m glad I’m not alone.
Hmmm, make a project to measure pollution, use a non-renewable resource like helium Instead of say an extendable pole to do it, seems to be the normal method.
The earth is making helium all the time from alpha decay of naturally occurring uranium and thorium. True that MRIs are using a lot of the helium that’s commercially isolated.
Use hydrogen.
Helium is considered non-renewable because once it is in the atmosphere it will escape into space, yes there is more being made naturally but we are using it faster then it is being made according to studies Ive seen. Hydrogen would work but less then $10 will get me 3 x 5 foot lengths of conduit and connectors so I could measure at 3 known heights, a balloon with a 15 foot cord in a stiff breeze will be blown sideways so the measurements would be at inconsistent heights.
In practice the natural mixing of gases means that CO diffuses to be the same density everywhere in a room (Consider that water with a molar mass of only 18 still results in the humidity in a room being constant). You can put your commercial CO monitor on the floor and it will work just as well.
It should be possible to craft a means to produce a set amount of CO in set volume from basic chemistry with good measurement and use that as a starting point or rough guide to get into the ball park. I used to get small 15psi tanks of 50ppm CO in N2 from a gas analysis firm Gastech in Perth, Western Australia. I designed a 4-20mA circuit with a novel monox sensor from UK for triggering fans for underground car parks – as some were pretty bad re ventilation. Was fun amplifying the 40nA/ppm current from the matchbox sized cheapo sensor back then (ie was a bit bigger hence cheaper than comparative output items from USA) early days though output pretty consistent. Better sensors nowadays of course and smaller too :-)
In the first place, what counts is the CO concentration where you breath, not 15 feet in the air. In the second place, the molecular mass of N2, which makes up ~80% of the air, is also 28. Unless you think gravity is separating O2 (molecular mass 32) from N2 you’ve got another think coming. Diffusion is so fast int the normal atmosphere that CO will be well mixed. It is only in sealed spaces where CO can accumulate that it is dangerous and if it does, the concentration at “nose” level is what matters.
There’s a LOT of published research on movement of CO in a room.
The correct siting of domestic CO alarms is VITAL.
You cannot ‘put one on the floor’ and expect it to detect
CO in the breathing zone.
PLEASE do some proper research before messing with the most
deadly chemical asphyxiant on the planet!
I do agree with one thing – 400ppm of CO will finish you off
in a few hours at most.
glad to see we’re finally back to caring about carbon monoxide which is pretty much created artificially wherever its enough to be a problem, and a “low hanging fruit” to address at a technological and local societal level. Deciding to be ever fearful of carbon dioxide, much of which is released simply by living creatures (including decay products) becomes such a big issue that it means scattering efforts too widely to make serious change.