The cycle is then repeated a sufficient number of {HEAD ~ times} to transfer a sufficient amount of {TAIL ~ gas} from the gas supply line to the on board storage, at the necessary pressures 
The cycle is then repeated a sufficient number of { HEAD ~ times } to transfer a sufficient amount of { TAIL ~ gas } from the gas supply line to the on board storage , at the necessary pressures
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH