Want this question answered?
I think a vacuum flask wouldn't qualify. They probably refer to compressed gas cylinders such as breathing apparatus, oxygen cylinders, and the like. In which the gas pressure is above atmospheric.
Self Containing Underwater Breathing Apparatus
A Internal Positive Pressure aid is an artificial aid for breathing used if you have problems with your muscles or lungs.
94664
Self Contained Breathing Apparatus Whereas SCUBA = Self Contained Underwater Breathing Apparatus
Breathing Apparatus with Self contained Compressed Air
SCUBA stands for Self Contained Underwater Breathing Apparatus. The B stands for breathing.
Scuba Breathing Apparatus.
asemhalingsapparaat
He invented an apparatus for breathing under water.
Self Contained Underwater Breathing Apparatus
CPT code for IPPB