{HEAD ~ The first and second valve apparatus} may be used in {TAIL ~ conjunction} with throttling apparatus applied to one or both of the first and second flow paths 
{ HEAD ~ The first and second valve apparatus } may be used in { TAIL ~ conjunction } with throttling apparatus applied to one or both of the first and second flow paths
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH