This standard covers accuracy, installation, calibration and verification of automatic tank gauges (ATGs) in custody transfer application in which the ATG is used for measuring the level of light hydrocarbon liquids, such as liquefied petroleum gas (LPG) transported aboard marine vessels (i.e., tankers and barges). The light hydrocarbon liquids covered in this standard may be pressurized or refrigerated, or both. This standard is applicable to natural gas liquid (NGL) and other petrochemical liquids where the storage and transportation requirements and the methods of measurement are similar to those for LPG gauging. This standard is not applicable to cryogenic liquids (below -100 °C) such as liquefied natural gas (LNG). Although the accuracy of marine automatic tank gauging is affected by some of the limitations described in Manual of Petroleum Measurement Standards (MPMS), Chapters 3.3 and 3.4, ATGs onboard LPG marine carriers can be used in custody transfer when no better, alternative measurement is available. The standard also covers the requirements for data collection, transmission, and receiving. This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.