ocr: FIRST-STAGE REGULATOR The first-stage regulator HIGH-PRESSURE reduces the pressure of AIR FROM TANK air from the tank sO that SPRING. WAIER iti isa always a certain -L - 7 - - - - amount above that of the water outside. Air PISTON. flows through the piston M - - I - - stem, and into the chamber that leads to PIPE LEADING TO the mouthpiece. When MOUIHPIECE the air pressure equals the combined pressure PISION STEM ofthe spring and the WAIER surrounding water, it pushes the piston back and prevents more air HIGH-PRESSURE AIR OUTLET TO entering the chamber. LOW-PRESSURE AIR PRESSURE GAUGE
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