Closure of the first valve apparatus prevents {HEAD ~ fluid communication} along {TAIL ~ the first flow path}, whereby fluid communication may be diverted to the second flow path, provided the second valve apparatus is in an open configuration 
along
Closure of the first valve apparatus prevents { HEAD ~ fluid communication } along { TAIL ~ the first flow path } , whereby fluid communication may be diverted to the second flow path , provided the second valve apparatus is in an open configuration
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH