Fire extinguishers usually fall under the provision that the landlord maintains as either by Housing Code, Building Code or Fire Code. Fire extinguishers can only be serviced by licensed personnel. The landlord should have this done on a yearly basis. Batteries to be change in smoke detectors and CO2 detectors can be required of the tenant. The landlord should have shown you how to do this. Check with your local city building department or Fire department for information.