<p>Measurement of single and multi-layer level in the hydrocarbon processing industries is commonly needed, but doing so accurately is often challenging. There is a great diversity of situations which require such level measurement, ranging from pure fluid to viscous, muggy and corrosive fluids.</p> <p>This new RP covers the selection and installation of instruments used for single and multi-layer level measurement that are encountered in upstream hydrocarbon facilities. This includes the overall and interface hydrocarbon process level measurement for liquids, recognizing the need to cater for emulsion and foaming issues.</p>