"Betty, you must have misunderstood so many of the posts... agreement they signed, about having it checked every year."
Actually, the agreement was to have the fire extinguisher refilled or recharged each year. The landlord wants it refilled if it was discharged or recharged once each year if not used to insure it will function properly when needed.
Most extinguishers will last 5 years or more, 10 pounders, 12 years. The post was about that the landlord claimed, it was the tenant's responsibility to have the extinguisher maintained and service because her daddy said a 'great tenant' was one who never bothers the landlord with such stuff!