When do we need a refill?
A Fire extinguisher is a passive product that needs to stay in a ready state at every point of time. Because a fire, though unlikely, can happen at any time.
There is ZERO margin for non performance, no second chance when the extinguisher is required to fight fire.
When your fire extinguisher has been used, even partially, you need to go for an authorised Ceasefire refill.
An empty or even partially used extinguisher, is useless at such a time. Ditto for an extinguisher that has been refilled by an unauthorised local vendor.