Like what I make? Want fewer sponsorship ad reads? Consider contributing to my Patreon at https://patreon.com/OurOwnDevices In a redo of last winter's unsuccessful experiment, I pit a modern "fire grenade" against a smaller, more realistic fire, while also testing its usefulness as an automatic, "sentinel" - style fire extinguisher. Will this unusual device finally deliver on its promise? Watch to find out! NOTES: -Apologies for the blurry image at the beginning; this was a last-minute shoot on location and I had no means (laptop etc.) of checking footage before leaving. -The SD card in the high speed camera was improperly formatted, meaning I had to test both grenades in "sentinel" mode in order to get both the regular and high-speed footage of the explosion (using the same card in each camera). This is why I wasn't able to test throwing the grenade directly into the fire. -The reason the fire re-ignited immediately after the grenade went off (both times) is that the logs retained a lot of heat - which the grenade does nothing to reduce. Theoretically, the grenade would be more effective against, for example, a liquid fire, but the amount of heat it had to be exposed to before it exploded suggests that even such a fire would spread beyond control by the time the grenade was activated - still rendering it useless.