Reducing agent can be conveyed back from the delivery device to {HEAD ~ the reservoir} via {TAIL ~ a return line} 
Reducing agent can be conveyed back from the delivery device to { HEAD ~ the reservoir } via { TAIL ~ a return line }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL