Also, the testing apparatus uses {TAIL ~ the rotation} of a threaded rod to apply the force necessary to create {HEAD ~ the face seal} 
Also , the testing apparatus uses { TAIL ~ the rotation } of a threaded rod to apply the force necessary to create { HEAD ~ the face seal }
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD