I must be weird, I asked to put the mask on and train, and I know simulated training is diff from real world but when i got my scba on full gear and a tank on i felt at home. the mask felt like a natural extension of myself, this is what I was meant to do, I drilled ran steps crawled up them, crawled under the trucks to simulate enclosed spaces ect. when my tank alarm went off simulating 5 mins of air...i asked if i could see how long i could conserve it i.e. as if i was trapped or hurt in a firefighter down situation. simulated a mayday call and sounded my pass alarm, it takes on average based on a univ. of phoenix study 22 mins to conduct a RIT rescue. so I extended that 5 mins of emergency air into a good 15 extra mins. a 20 min tank into 35 mins. i didnt take he mask and tank off til i ran it dry. granted this was in training, in real world scenerio inside a burning structure with flames smoke victims to locate ceiling and floor collasping, i may not be ale to be calm enough to stretch my oxygen that far.