Feedline assembly and asphalt circulation system for an asphalt distributor

摘要

A feed line assembly includes adjacent running or coaxial delivery and return conduits for transferring asphalt between a spray bar and a pump and tank of an asphalt distributor. The coaxial feed line assembly provides for one directional flow in each of the feed lines between the spray bar and the asphalt tank/pump. The circulating system can be operated in spraying and circulating modes. Asphalt flows through the delivery conduit to the spray bar and out through nozzles in the spraying mode and asphalt flows from the delivery conduit through the spray bar and is returned through the return conduit in the circulation mode. Asphalt is substantially static in the return conduit during the circulation mode. The coaxial feed line assembly serves as a heat exchanger to transfer heat from the delivery conduit to the return conduit and thereby prevent freezing of substantially static asphalt in the return conduit during spraying mode. A pressure differential between spraying and circulation modes control the position of a pressure relief valve connected to the return conduit to thereby control the flow through the circulating system.