Improvements to a portable fire extinguisher are disclosed. The improvements allow for frequent and simpler untrained and automatic self-servicing of a fire extinguisher. The improvements include an anti-bridging mechanism that fluffs, mixes or stirs the powder within the chamber to keep it in a liquefied state. Additional improvements include a larger opening to more quickly fill and inspect the powder within the chamber. Another improvement includes the use of a CO2 canister located external to the chamber to allow easier servicing or replacement of just the CO2 canister as well as the ability to maintain the chamber in an un-pressurized condition, allows for non-HASMAT shipping. These features will extend the service intervals while maintaining the fire extinguisher in a ready condition.