A gas blast switch has {HEAD ~ a housing} which encloses {TAIL ~ an arcing chamber}, an accumulator space and an expansion space 
encloses
A gas blast switch has { HEAD ~ a housing } which encloses { TAIL ~ an arcing chamber } , an accumulator space and an expansion space
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH