Method and a control arrangement for determining the status of a fluid tank

A method and a control arrangement for determining the status of a primary fluid tank or one or more secondary fluid tanks, each of the fluid tanks being arranged to contain a fluid or a mixture of fluids available in liquefied form and vaporised form and be connected to a second pressurized fluid conduit arrangement. The control arrangement determines a pressure drop (Δp) associated with the fluid flow through the second pressurized fluid conduit arrangement. When the pressure drop (Δp) exceeds a threshold, the control arrangement blocks the fluid flow from one of the fluid tanks to the second pressurized fluid conduit arrangement. Based on a subsequently determined pressure drop (Δp), the control arrangement determines whether said one of the primary and secondary fluid tanks is empty of liquefied fluid.