When the poppet valve is opened, {TAIL ~ fluid} flows through a flow channel in {HEAD ~ the valve assembly} 
When the poppet valve is opened , { TAIL ~ fluid } flows through a flow channel in { HEAD ~ the valve assembly }
OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD