a fluid pump unit operable to perform one of {HEAD ~ discharge} of fluid at least to the fluid channel unit and {TAIL ~ suction} of fluid at least from the fluid channel unit 
a fluid pump unit operable to perform one of { HEAD ~ discharge } of fluid at least to the fluid channel unit and { TAIL ~ suction } of fluid at least from the fluid channel unit
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH