A bonding material joins the plastic shell to the backing rings and {TAIL ~ sleeve} to prevent a space from forming beneath {HEAD ~ the plastic shell} that would become filled with the process fluid once it has permeated the plastic shell 
A bonding material joins the plastic shell to the backing rings and { TAIL ~ sleeve } to prevent a space from forming beneath { HEAD ~ the plastic shell } that would become filled with the process fluid once it has permeated the plastic shell
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH