When the displacement is finished, {HEAD ~ the valve} on {TAIL ~ the on board storage tank} will be closed and the pressure in the annulus released back to the surge tank 
on
When the displacement is finished , { HEAD ~ the valve } on { TAIL ~ the on board storage tank } will be closed and the pressure in the annulus released back to the surge tank
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH