A valve box 6 constitutes means for connecting the pump chamber 5 to a suction pipe via at least one check valve that allows {HEAD ~ fluid} to pass in {TAIL ~ direction} A 
to pass in
A valve box 6 constitutes means for connecting the pump chamber 5 to a suction pipe via at least one check valve that allows { HEAD ~ fluid } to pass in { TAIL ~ direction } A
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL OTH