a detector responsive to an air pressure condition within said passage to change {HEAD ~ a state} of {TAIL ~ said detector} under a predetermined pressure condition related to a fullness of said collector, said detector including: 
a detector responsive to an air pressure condition within said passage to change { HEAD ~ a state } of { TAIL ~ said detector } under a predetermined pressure condition related to a fullness of said collector , said detector including :
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH