The analyzer being programmed to derive, from the velocity measurement made within the single chamber, {TAIL ~ information} relating to the level of {HEAD ~ the gaseous substance} to be monitored 
The analyzer being programmed to derive , from the velocity measurement made within the single chamber , { TAIL ~ information } relating to the level of { HEAD ~ the gaseous substance } to be monitored
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH