Fire extinguishers need to be recharged periodically throughout their life, even if they haven't been used. ... For the most commonly used stored pressure dry chemical fire extinguishers, this internal examination and recharging is required at six and twelve years from the date of manufacture noted on the extinguisher.
New extinguishing agent (powder, gas, water or foam) is filled in the cylinder through a vacuum based process that fills the cylinder with exact quantity of extinguishing agent.
