Radar tank gauges are commonly referred to as microwaves – ultrasound and capacitance level sensors have faded with time due to the effectiveness and accuracy of microwave-based radar gauges. Their initial applications were for automatic tank gauging of marine petroleum tankers but were further developed to fit onshore storage tanks.
For high-performance requirements of custody transfer accuracy in tank gauging applications, the Frequency Modulated Continuous Wave (FMCW), also referred to as “Synthesized Pulse”, signal processing method is used in radar gauges. The FMCW method sometimes goes under the. FMCW can deliver an instrument-level gauging accuracy better than a millimetre over a 50+ meter range. The latest design has been miniaturised to small enclosures. The power requirements are reduced so that radar tank gauges can be made intrinsically safe and require only a 2-wire bus for power and communication.
FMCW technology makes a radar tank gauge accurate, but this is not enough on its own. Precision radar gauges must also have specially designed microwave antennas to deliver instrument accuracy and installed accuracy required by custody transfer standards. One important property of radar antennas is that they should be designed to drip off any condensation quickly. Therefore, antennas inside tanks require sloping surfaces to avoid the accumulation of condensate liquids. To understand this application, the reader is referred to American Petroleum Institute Standard (API MPMS ch. 3.1B, ed. 1) related to antenna design with no horizontal surfaces.
Petrik Naval is maker approved service station for Krohne, Endress+Hausser, Vega