Abstract: The invention relates to a method and arrangement for measuring at least one physical magnitude, such as temperature, flow or pressure of the cooling fluid flowing in an individual cooling element cycle (3) of a cooling element (1) in a metallurgical furnace. The arrangement includes a supply header (2) for distributing the cooling fluid and for feeding it to the cooling element cycles (3) of the cooling elements (1), and a collection header (4) for collecting and receiving cooling fluid from the cooling element cycles (3) of the cooling elements (1). The arrangement includes a survey line (5) that is by intermediation of a valve arrangement (6) in fluid connection with at least one cooling element cycle (3), so that the cooling fluid is conducted alternatively through the survey line (5) to the collection header (4) or past the survey line (5) to the collection header (4).