A sensor is provided for monitoring air pressure, with {TAIL ~ the sensor} issuing a pressure detection signal that is greater or lower than a preferred range of air pressure for air flow transmitted to {HEAD ~ the mask} 
A sensor is provided for monitoring air pressure , with { TAIL ~ the sensor } issuing a pressure detection signal that is greater or lower than a preferred range of air pressure for air flow transmitted to { HEAD ~ the mask }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD