The valve can only be switched while {HEAD ~ energy} is being transmitted from {TAIL ~ the service device} 
is transmitted from
The valve can only be switched while { HEAD ~ energy } is being transmitted from { TAIL ~ the service device }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL