In the absence of an open configuration of {HEAD ~ the second valve apparatus, fluid pressure increases} in {TAIL ~ the second flow path} 
In the absence of an open configuration of { HEAD ~ the second valve apparatus , fluid pressure increases } in { TAIL ~ the second flow path }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL