Device 3, wherein {TAIL ~ the valve} is contained with play between two grids mounted in {HEAD ~ series} with the port, and wherein the overall mean diameter of the apertures of each grid is less than the mean diameter of the port 
Device 3 , wherein { TAIL ~ the valve } is contained with play between two grids mounted in { HEAD ~ series } with the port , and wherein the overall mean diameter of the apertures of each grid is less than the mean diameter of the port
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH