A monitoring system in a medical facility provides an identification device to a patient and a data acquisition device to a health-care worker. The treated fuel has reduced levels of vanadium, nickel and other metals. A primary inter-ring connection is established for the particular service by a switch at the primary gateway node, but no inter-ring connection is established at the secondary gateway node. The retroreflector is arranged to direct the beam along a segment of the perimeter and return the beam along the segment.