Measurement Uncertainties of Level Gages for Liquefied Natural Gas

摘要

The measurement uncertainties of three types of gages commonly used in large liquefied natural gas storage and ship transport tanks have been studied and the results of this study are reported here. The types are bubbler, capacitance, and cable gages. Measurement uncertainties for various types can be determined but the test conditions must be carefully specified because many of the largest errors result from parameters external to the gaging device. The gage installation, the tank design, and the liquid properties all influence gaging accuracy. A modification of cable gage installations that should significantly improve gaging accuracy is presented. Intrinsic accuracies of some representative cable gages are reported from tests done at ambient temperature under nearly isothermal conditions.