wherein positioning of the plunger within {HEAD ~ the chamber} is artificially controlled by the positioning device to allow {TAIL ~ the volume} of the enclosure to be pre determinable 
wherein positioning of the plunger within { HEAD ~ the chamber } is artificially controlled by the positioning device to allow { TAIL ~ the volume } of the enclosure to be pre determinable
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH