When {TAIL ~ the parameter} to be sensed reaches a predetermined value or configuration, the switching apparatus may, by {HEAD ~ means} of electronic signals, cause the first valve apparatus to close 
When { TAIL ~ the parameter } to be sensed reaches a predetermined value or configuration , the switching apparatus may , by { HEAD ~ means } of electronic signals , cause the first valve apparatus to close
OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH