Optionally, a pressure sensor may be placed on the output side of the pump to provide {HEAD ~ an indication} of an empty reservoir or {TAIL ~ a substantial blockage} in the distribution system  
of
Optionally , a pressure sensor may be placed on the output side of the pump to provide { HEAD ~ an indication } of an empty reservoir or { TAIL ~ a substantial blockage } in the distribution system
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH