scope:

Description of Driving Event:

The 540A industrial oxygen analyzer continuously monitors the oxygen content from samples of atmosphere. Monitored areas include the orbiter processing facility, vertical assembly building, mobile launch platform, and the pads. When the oxygen level in these areas drops to an unsafe level of 19.5% or less, an audible/visible alarm is activated to warn personnel to evacuate the area. The oxygen analyzer has a sensing circuit which relays data to a supervisory box assembly which triggers the battery box assembly if an oxygen deficiency is detected. The battery box assembly supplies power to the warning beacon and sends a read out to the complex center console C-2 (in the launch control center). A component failure within the oxygen analyzer due to fatigue/shorting may cause an erroneous high output signal when the oxygen level is below 19.5%, resulting in no alarm warning. Personnel may enter/work in the area, unaware of the low oxygen level, and become asphyxiated.