In a vacuum elevator, air pressure is used to lift the elevator cab to the appropriate floor. They are more reliable and safer than other types of elevators. Typically, an air compressor is required to supply sufficient atmosphere to the pneumatic system to complete the task. The compressor draws air from the surrounding environment and stores it in receiver tanks. Pipes and valves are used to distribute them throughout the system. Air Pressure is a force imposed on an object by the weight of air molecules. If there is no air pressure, the cab will be grounded and will be unable to move up and down.