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