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