{HEAD ~ The unidirectional pressure sensitive valve} 2, in which {TAIL ~ said device} is a pump 
{ HEAD ~ The unidirectional pressure sensitive valve } 2 , in which { TAIL ~ said device } is a pump
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH