During a switching off operation, the moveable contact member moves out of the arcing chamber and quenching gas flows from {TAIL ~ the accumulator space} into {HEAD ~ the expansion space}, through the arcing chamber, i.e. the nozzle 
During a switching off operation , the moveable contact member moves out of the arcing chamber and quenching gas flows from { TAIL ~ the accumulator space } into { HEAD ~ the expansion space } , through the arcing chamber , i.e. the nozzle
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH