What is the difference between internal and process/external control when using a circulator?

Internal (or jacket) temperature refers to the oil leaving the circulator to be circulated through the vessel jacket – it is inside the circulator, not inside the vessel.

An external (or process, contents or reactor) temperature reading is from a temperature probe external to the circulator, typically a Pt100 in a Reactor-Ready vessel plugged into the circulator.

Huber units with Pilot ONE controllers require at least the E-grade (software level) ‘Exclusive’ to have the option of control via the process temperature sensor rather than just the internal temperature sensor.