Thats how you use the Pressure-Guard TS250 measuring system (diving sports).
... and this is how you use the Pressure-Guard test system for breathing protection AS137:
PG TS 250-3 on a diving mission up to 260ft in a pressure chamber.
This special variant with the installement of an utter power supply and usage under 48V in the pressure chamber fulfilled the norm for a stable overpressure mode. Also the measurements of temperature and air humidity are recorded in the EN250 cold water test. A minicam records the behavior of the breathing sensor and detects the "freezing".
With this Pressure-Guard offers an essential documentary device for verifying- and technical testing centres as well as for industries in the inline quality check department.