These rules apply to ABC dry chemical extinguishers only.
NFPA 10 defines the maintenance procedures required for portable fire extinguishers. All multi-purpose ABC extinguishers must have maintenance performed on an annual basis. After performing these steps, the technician will apply a new colored tag (Including his or her license information) to the extinguisher to clearly specify that maintenance has been performed.
Every six years the fire extinguisher must be completely torn down (taken apart), recharged and rebuilt. During this process, key parts within the extinguisher are replaced. A special maintenance sticker is added to the extinguisher cylinder to record the date and licensing information of the technician performing the six year maintenance.
Every twelve years the fire extinguisher must have a pressurized hydro-test performed to ensure the stability of the cylinder. In addition to the hydro test, all other steps required for a typical six year maintenance must also be performed at this time.