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