An extracorporeal treatment assembly including a pump and a controller wherein an extracorporeal circuit is mounted to the assembly, the controller causes the assembly to: control the pump to pump liquid through the passage and the flow coupling; collect actual fluid pressure data; store circuit type data uniquely corresponding to a certain type of extracorporeal circuit; determine a dimension of the certain type of extracorporeal circuit; determine an expected fluid pressure for the certain type of extracorporeal circuit; based on a comparison of the actual fluid pressure data and the expected fluid pressure, determine whether the certain type of extracorporeal circuit corresponds to the actual extracorporeal circuit.