{HEAD ~ Device} 3, wherein {TAIL ~ 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 each grid is less than the mean diameter of the port 
{ HEAD ~ Device } 3 , wherein { TAIL ~ 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 each grid is less than the mean diameter of the port
HEAD HEAD HEAD HEAD HEAD OTH OTH REL TAIL 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 OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH