{HEAD ~ A pressure release opening} in {TAIL ~ the seal cover} is in fluid communication with the circumferential passage 
in
{ HEAD ~ A pressure release opening } in { TAIL ~ the seal cover } is in fluid communication with the circumferential passage
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH