Summary Produced water is a major challenge in the oil and gas industry, especially with the aging of oil fields. Proper treatment of produced water is important in reducing the environmental footprint of oil and gas production. On offshore platforms, hydrocyclones are commonly used for produced-water treatment. However, maintaining the efficiency of hydrocyclones subjected to plant disturbances is a difficult task owing to their compact nature. This paper describes a new experimental test rig built at the Department of Mechanical and Industrial Engineering at the Norwegian University of Science and Technology for testing industrial-scale hydrocyclones. The test setup can emulate first-stage separation and create plant disturbances, such as changes in flow rate, oil concentration, and oil droplet distribution at the inlet of the hydrocyclones. Also, the setup is capable of testing different control algorithms, which helps to maintain the efficiency of hydrocyclones in the presence of such disturbances. The test rig is equipped with various instruments that can monitor such parameters as pressure, flow, temperature, and oil concentration. A typical pressure drop ratio (PDR) control scheme for hydrocyclones is tested in the test rig, which can control the disturbances in the inflow rate. The PDR control scheme does not detect disturbances in the inlet oil concentration and changes in droplet distribution, and these scenarios are shown experimentally in this paper.