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