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