The apparatus 1 wherein {HEAD ~ the three way valve} is located downstream of {TAIL ~ the pump} means 
is located downstream of
The apparatus 1 wherein { HEAD ~ the three way valve } is located downstream of { TAIL ~ the pump } means
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH