no open flame; fire prohibited; flammables!
A set phrase used on signs and warnings to indicate that fire, sparks, or ignition sources are strictly forbidden. Often seen in places with flammable materials.
There is a 'No Open Flame' sign at the gas station.
This warehouse is a no-fire zone.
禁煙 specifically prohibits smoking, while 火気厳禁 bans all sources of fire or ignition.
火の用心 is a general caution to be careful with fire, often used in fire prevention campaigns, whereas 火気厳禁 is a strict prohibition.
Compound of 火気 (fire, flame) and 厳禁 (strict prohibition).