A new concept in level control is presented based on a no-moving-part fluidic valve, having the potential for extending the operating envelope of intensified separators or improving level control response and reliability in conventional separators. Operation is reliable and automatic with fast response, no power requirement and a solids handling capability. The system is based on the symmetrical turn-up vortex amplifier, or STuVA, and its basic design and operation is described. Two important performance parameters are identified as a flow ratio, which represents system turn-down, and a pressure recovery factor. Tests separating air, water and oil in a 0.9 m diameter horizontal vessel confirm the basic operation of the system. A flow instability phenomenon discovered in a simple 2-port STuVA design favours use of a more complex 8-port design, constructed in a compact laminated axi-symmetric arrangement, suitable for high pressure operation and convenient for installation in separator systems. Equations which describe the basic non-cavitating and cavitating performance of the STuVA are given, together with the results of tests done to establish how important geometrical parameters affect the performance. The designs tested demonstrate reasonable performance such that they can be usefully applied to a separation system, although further work will develop a fuller understanding of STuVA characteristics.