Hackaday Prize Entry: Gas Grenade Helps Instead Of Exploding

If someone lobs a grenade, it’s fair to expect that something unpleasant is going to happen. Tear gas grenades are often used by riot police to disperse an unruly crowd, and the military might use a smoke grenade as cover to advance on an armed position, or to mark a location in need of an airstrike. But some gas grenades are meant to help, not hurt, like this talking gas-sensing grenade that’s a 2015 Hackaday Prize entry.

Confined space entry is a particularly dangerous aspect of rescue work, especially in the mining industry. A cave in or other accident can trap not only people, but also dangerous gasses, endangering victims and rescuers alike. Plenty of fancy robots have been developed that can take gas sensors deep into confined spaces ahead of rescuers, but [Eric William] figured out a cheaper way to sniff the air before entering. An MQ2 combination CO, LPG and smoke sensor is interfaced to an Arduino Nano, and a 433MHz transmitter is attached to an output. A little code measures the data from the sensors and synthesizes human voice readings which are fed to the transmitter. The whole package is stuffed into a tough, easily deployed package – a Nerf dog toy! Lobbed into a confined space, the grenade begins squawking its readings out in spoken English, which can be received by any UHF handy-talkie in range. [Eric] reports in the after-break video that he’s received signals over a block away – good standoff distance for a potentially explosive situation.

With the expanding supply of cheap sensors available these days, the possibilities are endless for ideas like this. It wouldn’t be that hard to add temperature, humidity and pressure sensors to the grenade, or maybe even the alcohol and ammonia sensors from this sensor suite. Add in sensors for things like particulates, vibration, and radiation, and pretty soon you’ve got a grenade that could do a lot of good.

The 2015 Hackaday Prize is sponsored by:

23 thoughts on “Hackaday Prize Entry: Gas Grenade Helps Instead Of Exploding

  1. Sorry the overlords are not in the business of saving they are in the business of killing. the funding for your department will now be cut and you’re FIRED. not just kidding…btw great work

  2. Awesome idea, I like how it transmits the information and the payload. If you are considering explosive environments though you may want to look into IECEX certification as a guideline for designing the electronics with the view of certification later. It will give you background into what risks there are and information on what is required so you dont make a bad situation worse.

    Sadly this has the flip side of increasing the cost and complexity of the project significantly. Damned if you do, damned if you dont unfortunately.

  3. Interesting idea, but I’d change the way it reports, alerts have priority and get sent immediately after detection, the rest would just be “gas OK” with a much slower repeat cycle. Agree with the need of a possibility of adding more sensors, possibly a modular system with plug&play capability.
    Also, I’d simplify the alert quantification to “low”, “medium” and “high”.
    Last but no least, some blinky LEDs so that you can find and retrieve it once the mission is over ;-)

      1. The problem with trusting your nose on something like H2S is that our sense of smell really sucks. Your nose acclimates to a given environment and your brain starts ignoring constant odors, so as the gas levels change your nose blissfully reports nothing new until (especially in H2S scenarios) *thud* out and dead.

        1. H2S specifically will paralyze the olfactory nerve above a certain concentration, so the smell “goes away” even though it could be at a fatal concentration.

          Multi-head gas monitors (H2S, CO, LEL, O2, SO2, etc) are quite common, so it is conceivable that this design could easily be extended to include more types of monitors. Great concept!

    1. Not to mention the MQ type sensors have a little heating element in them. If it gets too hot for some reason, or if it fails and causes a small spark, it could ignite the flammable gas you are trying to measure.

      1. The MQ-2 datasheets do specify that they can be used for industrial combustible gas monitoring and leak detection. This risk is inherent to those applications so I assume it is reasonably abated.

      2. Yeah, even though the data sheet for the MQ-2 states it can be used for industrial combustible gas monitoring, no manufacturer would use it directly in that application. It would never pass US Bureau of Mines or IECEX certification for that. But there are sensors available that would (have) passed the testing that he could use.

        1. The USBM was “closed” in 95′, with it’s duties re-assigned to the DoE, USGS, BLM and NIOSH. A division of the NIOSH called the National Personal Protective Technology Laboratory (NPPTL) handles testing of this type of device for use in US mines.

    1. I bet so! You could even take a regular household alarm and stuff its guts in the same dog toy, since you know you’ll be able to hear it with only a single door or window between you and it.

  4. eevblog did a teardown a while back of a handheld mining gas sensor, showing some of the design issues that make it safe for use in such an environment. I suspect no mining company is going to touch this unless it meets those ratings.

  5. I’ve worked in emergency response, and while I agree there is room for improvement, this concept is fantastic. Much better than sending in someone first in SCBA to place a sensor. Next generation would be to have a camera at cardinal points and a liquid detector.

  6. Really cool. I’d also love to see an O2 sensor on the “grenade”. Plenty of accidents where the gasses aren’t toxic or explosive, but still dangerous because they have no smell and displace most of the oxygen.

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