A liquid drain withdraws the liquid constituent from {HEAD ~ the vessel} at a rate determined by {TAIL ~ a level assembly} 
A liquid drain withdraws the liquid constituent from { HEAD ~ the vessel } at a rate determined by { TAIL ~ a level assembly }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL