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