TM 5-4220-226-14&P
a. The breathing medium flows through the air hose portion of the umbilical to the main air inlet port,
which connects with the one-way adapter and then the side block assembly.
b. The flow continues into the side block assembly. A through passage in the side block assembly is
always open to supply the demand regulator whenever the air supply is pressured up. The steady flow knob
controls flow from the passage in the side block through the muffler air train into the helmet interior. In cold
water, the face port fogs up from the diver's face warmth and moisture. Directing the incoming air onto the lens
clears this fogging.
c. The demand regulator functions like a standard Self-Contained Underwater Breathing Apparatus
(SCUBA) unit. The dial-a-breath knob allows the diver to control the regulator for a wide range of air supply
pressures. Diver control allows for the least breathing resistance. The diver's exhalation gases exit the oral-
nasal mask Into the demand regulator and out through the exhaust.
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