SCBA (self-contained breathing apparatus) systems and components supply breathable air from a self-contained unit that is worn on a worker's back or waist. The unit includes a tank and respirator, allowing the worker to move freely without the need to connect to an airline. Air tanks provide breathable air for up to an hour. Industrial SCBA systems are often worn with other protective clothing by firefighters, emergency responders, and people working in chemical manufacturing. SCBA cylinder carts store and transport air cylinders.