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