When flapper 115 is forced open by {HEAD ~ gas pressure}, the current flowing between {TAIL ~ electrode} 140 and electrode 142 is interrupted 
When flapper 115 is forced open by { HEAD ~ gas pressure } , the current flowing between { TAIL ~ electrode } 140 and electrode 142 is interrupted
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH