API MPMS 3.6

Abstract

This standard covers selection, installation, commissioning, calibration and verification of Hybrid Tank Measurement Systems (HTMSs) for the measurement of level, static mass, observed and standard volume, and observed and reference density in tanks storing petroleum and petroleum products. It is up to the user to define which measurements are required for custody transfer or inventory control purposes (standard volume, mass, or both). Therefore, this standard also provides a method of uncertainty analysis, with examples, to enable users to select the correct components and configure an HTMS to more closely address the intended application. (See Appendix B.) <br>This standard covers HTMSs for stationary storage tanks storing liquid hydrocarbons with a Reid Vapor Pressure below 15 psi (103.42 kPa). This standard applies to vertical cylindrical tanks, and can also be applied to tanks with other geometries (e.g., spherical and horizontal cylindrical) which have been calibrated by a recognized oil industry method. Examples of uncertainty analysis for spherical and horizontal cylindrical tanks are also given in Appendix B. <br>This standard does not apply to pressurized tanks or marine applications. This standard covers the installation and calibration of HTMSs for custody transfer and inventory control. <br>Note: The term "mass" is used to indicate mass in vacuum (true mass). In the petroleum industry, it is not uncommon to use apparent mass (in air) for commercial transactions. Guidance is provided on the calculation of both mass and apparent mass in air (See Appendix A).