Even if you never have to use it, you should get rid of a fire extinguisher that’s 10 years old. If you have a rechargeable model, have it serviced about every six years.
The contents of a portable fire extinguisher are pressurized, and over time, they can de-pressurize, leaving the unit useless when you need it the most.
If your home is humid, you might need to replace your fire extinguishers more often. In the meantime, check the extinguisher every month for corrosion, which can cause an air and contents leak.