It is important to understand the difference between rechargeable fire extinguishers and non-rechargeable fire extinguishers. Non-rechargeable fire extinguishers are intended for one time use only. If you use your non-rechargeable fire extinguisher even once, you must replace it. It will not be effective in fighting a fire. Never test a fire extinguisher by using it. Once used, it will gradually lose pressure and will not be fully charged for use in an emergency. Rechargeable fire extinguishers are intended to be recharged once they are used, or when it loses pressure over time. Once a year or according to your local fire codes, rechargeable fire extinguishers in business or commercial applications should be serviced by a certified fire equipment dealer, in accordance with the service manual and as identified on the fire extinguisher label. If it is discharged, a rechargeable fire extinguisher must be refilled by a certified fire equipment dealer regardless of how much of the contents were used.