API MPMS 3.6:2001(R2017) pdf download.Manual of Petroleum Measurement Standards Chapter 3—Tank Gauging
A Hybrid Tank Measurement System (HTMS) is a method of combining direct product level measured by an automatic tank gauge (ATG), temperature measured by an automatic tank thermometer (ATT), and pressures from one or more pressure sensors. These measurements are used, together with the tank capacity table and applicable volume and density correction tables, to provide level, temperature, mass, observed and standard volume, and observed and reference density. The product level is directly measured by the ATG. The product temperature is directly measured by the ATT. The true (observed) density is determined from hydrostatic pres- sure measured by the pressure sensor(s) and the product height above the bottom pressure sensor, as measured by the ATG. Total static mass is computed by a hybrid processor from the true density and the tank capacity table. Gross observed volume, standard volume, and reference density are computed using industry practice for static calculations (See MPMS Chapter 12.1).
2 Scope
This standard covers selection, installation, commission- ing, 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.) This standard covers HTMSs for stationary storage tanks storing liquid hydrocarbons with a Reid Vapor Pressure below 15 psi (103.42 kPa).
4 Definitions
For the purpose of this standard, the following definitions apply: 4.1 HTMS: A Hybrid Tank Measurement System (HTMS) is a system which uses the product level measured by an auto- matic tank gauge (ATG), the product temperature measured by an automatic tank thermometer (ATT), and the static head of the liquid measured by one or more pressure sensors. These measurements are used, together with the tank capacity table and the product volume/density correction tables, to provide (i.e., display and/or print out) level, temperature, mass, observed and standard volume, and observed and refer- ence density. 4.2 hybrid processor: The computing device compo- nent of the HTMS which uses the level, temperature, and pressure sensor measurements of the HTMS, in addition to stored tank parameters, to compute density, volume, and mass. 4.3 hybrid reference point: A stable and clearly marked point on the outside of the tank wall, from which the position of the pressure sensor(s) is (are) measured. The hybrid refer- ence point is also measured relative to the datum plate.
API MPMS 3.6:2001(R2017) pdf download
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