The servicing of fire extinguishers, which are pressure vessels with operating pressure of100 to 2000 PSI, demands trained, qualified, and licensed service technicians using proper equipment and materials. The maintenance of portable fire extinguishers is governed by DOT (Department of Transportation) and applicable standards of NFPA (National Fire Protection Association). Aidant strictly enforces these minimum guidelines to ensure that the fire extinguishers operate properly and safely.