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