Switching {TAIL ~ apparatus}, including sensors for detecting the condition of the system, operate to close the first valve apparatus in {HEAD ~ response} to pre determined threshold values of such condition 
Switching { TAIL ~ apparatus } , including sensors for detecting the condition of the system , operate to close the first valve apparatus in { HEAD ~ response } to pre determined threshold values of such condition
OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH 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