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