{TAIL ~ The amount} of {HEAD ~ gas} released each time the valve opens is used to determine how much gas is produced during fermentation, in the manner described above 
{ TAIL ~ The amount } of { HEAD ~ gas } released each time the valve opens is used to determine how much gas is produced during fermentation , in the manner described above
TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH