A method of configuring a vortex flow control device comprising a vortex chamber, an inlet and an outlet arranged at one end of the vortex chamber, wherein the method comprises the steps of: setting a target maximum flow rate (F T-MAX) through the outlet for a predetermined pressure at the inlet; setting a target vortex initiation flow rate (F T-VI) through the outlet at which vortex flow within the vortex chamber initiates; determining the actual maximum flow (F A-MAX) rate through the outlet for the predetermined pressure at the inlet; determining the actual vortex initiation flow rate (F A-VI) through the outlet; determining an error parameter based on at least one of the actual maximum flow rate (F A-MAX) and the actual vortex initiation flow rate (F A-VI) and at least one of the target maximum flow rate (F T-MAX) and the target vortex initiation flow rate (F T-VI); comparing the error parameter against a target condition (C T); and if the error parameter fails to satisfy the target condition (C T), determining a respective sensitivity parameter relating to the impact of a change of each of a plurality of characteristics of the vortex flow control device on the actual maximum flow rate (F A-MAX) and/or the actual vortex initiation flow rate (F A-VI), the characteristics comprising an inlet area of the inlet, an outlet area of the outlet, and a diameter of the vortex chamber, wherein the sensitivity parameter relates to the effect of the change of each of the plurality of characteristics on the error parameter; and modifying at least one of the characteristics in accordance with the sensitivity parameter so as to vary at least one of the actual maximum flow rate (F A-MAX) and the actual vortex initiation flow rate (F A-VI). setting a target maximum flow rate (F T-MAX) through the outlet for a predetermined pressure at the inlet; setting a target vortex initiation flow rate (F T-VI) through the outlet at which vortex flow within the vortex chamber initiates; determining the actual maximum flow (F A-MAX) rate through the outlet for the predetermined pressure at the inlet; determining the actual vortex initiation flow rate (F A-VI) through the outlet; determining an error parameter based on at least one of the actual maximum flow rate (F A-MAX) and the actual vortex initiation flow rate (F A-VI) and at least one of the target maximum flow rate (F T-MAX) and the target vortex initiation flow rate (F T-VI); comparing the error parameter against a target condition (C T); and if the error parameter fails to satisfy the target condition (C T), determining a respective sensitivity parameter relating to the impact of a change of each of a plurality of characteristics of the vortex flow control device on the actual maximum flow rate (F A-MAX) and/or the actual vortex initiation flow rate (F A-VI), the characteristics comprising an inlet area of the inlet, an outlet area of the outlet, and a diameter of the vortex chamber, wherein the sensitivity parameter relates to the effect of the change of each of the plurality of characteristics on the error parameter; and modifying at least one of the characteristics in accordance with the sensitivity parameter so as to vary at least one of the actual maximum flow rate (F A-MAX) and the actual vortex initiation flow rate (F A-VI). determining a respective sensitivity parameter relating to the impact of a change of each of a plurality of characteristics of the vortex flow control device on the actual maximum flow rate (F A-MAX) and/or the actual vortex initiation flow rate (F A-VI), the characteristics comprising an inlet area of the inlet, an outlet area of the outlet, and a diameter of the vortex chamber, wherein the sensitivity parameter relates to the effect of the change of each of the plurality of characteristics on the error parameter; and modifying at least one of the characteristics in accordance with the sensitivity parameter so as to vary at least one of the actual maximum flow rate (F A-MAX) and the actual vortex initiation flow rate (F A-VI).