Further, it is preferred that {TAIL ~ the air} be available at at least about 0.5 standard cubic feet per {HEAD ~ minute}  
Further , it is preferred that { TAIL ~ the air } be available at at least about 0.5 standard cubic feet per { HEAD ~ minute }
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH