This Recommendation specifies the metrological and technical requirements and test procedures for automatic level gauges for storage tanks. Storage tanks include all the shapes referenced in OIML R 71 [5] e.g. vertical and cylindrical storage tanks, and pressurized storage tanks (spheres, spheroid, bullets). The storage tanks may be refrigerated or heated. The metrological purpose of tank level measurements is the application in conjunction with tank calibration tables for the determination of liquid volume received from, delivered to, or contained in stationary storage tanks