{HEAD ~ The output signals} from transducers and are used by data processing unit to compute {TAIL ~ the total concentration} of hydrocarbon gases and vapors and the concentration of methane gas within cells and  
{ HEAD ~ The output signals } from transducers and are used by data processing unit to compute { TAIL ~ the total concentration } of hydrocarbon gases and vapors and the concentration of methane gas within cells and
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH