The improvement 4, wherein {HEAD ~ each said pressure responsive device} includes means for driving said valve therefor toward open position upon an increase in {TAIL ~ the pressure signal} thereto 
The improvement 4 , wherein { HEAD ~ each said pressure responsive device } includes means for driving said valve therefor toward open position upon an increase in { TAIL ~ the pressure signal } thereto
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH