"A SELF CONTAINED UNIT USED TO SIMULATES AN INCREASE IN ALTITUDE TO A PREDETERMINED VALVE ABOVE THE PRESET ALTITUDE OF THE ACTUATOR. AMBIENT OUTSIDE AIR IS BLED BACK AT A CONTROLLED RATE INTO THE TEST CHAMBER TO SIMULATE A RATE OF DECREASING ALTITUDE; O/A DIM: 16.000 IN. W.,14.000 IN. H.,12.000 IN. D.; WT: 24 LBS"