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