These valves are closed when the separator tube 16 is inserted into {HEAD ~ the collection tube} 10 as shown in FIG 7, but opened as the separator tube 18 is removed from the collection tube 10 as shown in FIG 7a so as to allow air to enter {TAIL ~ the collection tube} 
These valves are closed when the separator tube 16 is inserted into { HEAD ~ the collection tube } 10 as shown in FIG 7 , but opened as the separator tube 18 is removed from the collection tube 10 as shown in FIG 7a so as to allow air to enter { TAIL ~ the collection tube }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD 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 OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL