The Joker is a popular character in the Batman franchise, and at times uses poisonous gases as part of his criminal repertoire. That inspired this fun project by [kutluhan_aktar], which aims to monitor the level of harmful gases in the air.
The project doesn’t use just one gas sensor, but several! It packs the MQ-2, MQ-3, MQ-4, MQ-6, and MQ-9. This gives it sensitivity to a huge variety of combustible gases, as well as detecting carbon monoxide. The sensors are read by an Arduino Nano, which displays results on an RGB LED as well as an attached IPS screen.
Readings from each sensor can be selected by using an infrared remote. In order to best work as a safety device, however, it could be more useful to have the Arduino automatically cycle through each sensor, checking them periodically and raising an alarm in the event of a high reading.
The whole project is built on a custom PCB which is artfully constructed with an image of the Joker himself. It helps to make the project a bit more of a display piece, and speaks to the aesthetic skills of its creator.
It’s a fun build, and one that could be mighty capable with a few software tweaks. With that said, if you’re working in a space with real hazards from combustible gases, it may be worth investing in some properly rated safety equipment rather than relying on an Arduino project.
Incidentally, if you’d like to improve the results from using such gas sensors, we’ve looked at that in the past. Video after the break.
I love the artistry and I appreciate the effort, but honestly are any of these poisonous gases a concern in your life?
MQ-2 Smoke Gas LPG Butane Hydrogen Gas Sensor Detector Module For Arduino
MQ-3 Alcohol Ethanol Sensor Breath Gas Detector Ethanol Detection for Arduino
MQ-4 Methane Gas Sensor Natural Coal Co methane detector module For Arduino
MQ-6 LPG Gas Sensor Isobutane Propane Sensor For Arduino & Raspberry
MQ-9 Combustible Gas Sensor Detection Carbon Monoxide Alarm Module
CO detector? I guess. The rest? Seems very niche and situations where I’d want a calibrated instrument that is properly maintained.
I’m curious how these were triggered in the video other than the butane lighter. A LED directly above the appropriate sensor would have made this obvious. A faster response would have helped too.
But…I’ve built something less much beautiful that only monitors CO2 so I will not dismiss this at all.
“MQ-4 Methane Gas Sensor Natural Coal Co methane detector module For Arduino”
“honestly are any of these poisonous gases a concern in your life?”
Not a bean fan, eh?
Nit: CO is also combustible, good ol’ coalgas and syngas.
Probably that’s how the sensor works, anyway: catalytic oxidation or something.
Coalgas is much more than CO though – full of volatile Hydrocarbons. H, CH4, C2H4. And Syngas has Hydrogen. Anyway, CO detectors are not typically used as combustible detectors, because CO is toxic long before it’s flammable. LEL for CO is 12.5%VOL, and it’s starting to get dangerous to breathe already at 100ppm (0.01%VOL), so if you get a significant CO leak, you’re in trouble _long_ before combustion is an issue.
I checked the datasheets and it seems like its MOS type sensors, not catalytic.
one nitpick – the toxicity of CO depends on both concentration and exposure time.
Obviously, and that’s why I stated “starts to get dangerous already at 100ppm”. Doesn’t mean it stops being dangerous above that, and that it’s non-toxic below that, but at that point, you will want to evacuate the premises rather quickly. The permissible exposure limit for CO is 25ppm for average concentration over one work day, and short exposures should not exceed 100ppm in Norway. (OSHA is 50ppm over a work day)
“safety device”. Heh. Yeah. Neat project, but _not_ a safety device. Cheap gas sensor capsules need calibration typically something like 1-4 times pr year to stay anywhere near accurate.
I had a CO alarm go off in my apartment many years ago, not long after I had moved in. My father borrowed (left work with one day) a confined space gas meter. Little thing the size of a large flip phone. We could find leaks in the window seals by seeing where levels went to zero, and narrowed down the problem to the stove pilot. As long as there wasn’t much of a breeze in the kitchen, the draft was enough to carry it out the hood vent.
That industrial device was calibrated and certified every six months.
The CO detector the maintenance crew used, on the other hand, was “calibrated” when they remembered to. By guys smoking the whole time. I laughed in their face when they told me there was no CO problem, because their meter measured -4 ppm. F’in vacuum energy in that kitchen. They were less happy when I asked the fire department to measure it, and that guys detector went off when I opened the door.
Just looked at the MQ-2-datasheet and yeah, i am still sceptical about these sensors. They are (were?) really cheap on the usual chinese platforms but what about tolerance, aging, calibration, …? Did somebody with the right equipment made some measurements? I mean this project is nice, but i really wonder how accurate the measurements are. I don’t know how easy (and how expensive!) it is to buy test gas with certified concentrations, but while for some chemicals (like methane, …) it might be a doable way to calibrate these sensors (just do it outside and don’t smoke…) for others (carbon monoxyde, …) i don’t think you can even get the needed gas as a non-professionnel and that is probably a good thing…
I had a Kiddie/Nighthawk CO/EG alarm when I had gas heat and stove. It recommended checking the CO every year, and was good for 5 to 10 years how it left the factory. They set it’s alarm level low so it would be good that long.
The “test procedure” recommended lighting a match, blowing it out, and holding the smoldering bit near the sensor. It would very rapidly detect a level over 100ppm and became very loud.
It did not have any advice on how to check the methane and propane sensor. I’m guessing that one left the factory with a better guarantee.
Gas meter checks are common for refinery workers, it’s called a “Bump test”. 4 gas mixes aren’t too spendy, ~$40 for a small can.
https://www.majorsafety.com/products/gasco-bump-it-bump-test-gas
This isn’t a calibration, it’s just a check to make sure that it responds to the hazard.
Bump test gas is typically something like 5-10% accurate, and the expected response varies with ambient pressure, humidity and temperature. I think a response within 20-40% accuracy would be acceptable for a bump test, depending on the level of control one has over the environment and how the gas is applied.
Also, depending on the sensor technology, it might be severe cross-sensitivity with different gases. Quite a lot of traps for young players in this field.
Disclaimer: I design gas detectors for a living.