Abstract: A recirculation device permits a relatively inaccessible fluid housed in a vessel having an access port to be evaluated externally of the vessel; the device provides a recirculating flow path extending from inside the vessel passing through the access opening to an external fluid loop, and back to the vessel via the same access opening; the flow path comprises an upstream path and a downstream path, which paths are discrete separate paths throughout their length; flow in the recirculating flow path is induced in the external fluid loop; the fluid can be sensed directly in the fluid loop or a sample can be removed from the loop for evaluation.