Making the cross sectional shape of the channel 46 a segment of a true circle also contributes to {HEAD ~ the functional characteristics} of {TAIL ~ the valve} 
of
Making the cross sectional shape of the channel 46 a segment of a true circle also contributes to { HEAD ~ the functional characteristics } of { TAIL ~ the valve }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL