{HEAD ~ The amount} of {TAIL ~ gas} that escapes each time is measured and programmed into control means 60 
of
{ HEAD ~ The amount } of { TAIL ~ gas } that escapes each time is measured and programmed into control means 60
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH