GB/T 25964-2010 Petroleum and liquid petroleum products — Method for measuring the volume, density and mass of oil in vertical cylindrical tanks using a hybrid tank measurement system

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Card type: Test method

1. Method number / full name / English name / replacement relationship

• Standard number: GB/T 25964—2010
• Chinese name: Petroleum and liquid petroleum products — Method for measuring the volume, density and mass of oil in vertical cylindrical tanks using a hybrid tank measurement system
• English name: Petroleum and liquid petroleum products—Determination of volume, density and mass of the hydrocarbon content of vertical cylindrical tanks by hybrid tank measurement systems
• Adoption relationship: Modified adoption of ISO 15169:2003 (MOD)
• Replacement relationship: not provided in the available source (the foreword does not give the old standard number replaced)
• Publication/implementation: published on 2011-01-10, implemented on 2011-05-01
• Proposed by/under the jurisdiction of: proposed by the National Technical Committee for Standardization of Petroleum Products and Lubricants (SAC/TC 280); under the jurisdiction of SAC/TC 280/SC 2
• Drafting organizations: Sinopec Research Institute of Petroleum Processing, Beijing Ruisai Great Wall Aviation Measurement and Control Technology Co., Ltd.; participating drafting organization: Sinopec Zhejiang Petroleum Branch
• Drafters: Wei Jinxiang, Dong Haifeng, Huang Cenyue, Xu Gufu

2. Scope of application and non-applicability

• Applicable: provides guidelines for the selection, installation, commissioning, calibration and verification of a hybrid tank measurement system (HTMS); it can measure the liquid level, static mass, metered volume and standard volume, as well as metered density and standard density, of petroleum and petroleum products stored in tanks, so as to meet the needs of oil custody transfer measurement.
• Applicable objects: stationary vertical cylindrical tanks whose stored oil has a Reid vapor pressure (RVP) lower than 103.42 kPa.
• Not applicable: pressure tanks or ship compartment measurement.
• Note 1: the term "mass" refers to mass in vacuum (true mass); in the petroleum industry, apparent mass (in air) is often used for commercial custody transfer, and the standard also provides calculation methods for mass and apparent mass in air (see Annex A).
• Note 2: the calculation method of this standard can also be used for tanks of other shapes (already calibrated by national standard methods); Annex B gives calculation examples of uncertainty analysis for spherical and horizontal cylindrical tanks.

3. Method principle

• HTMS uses an automatic level gauge (ALG) to measure the oil liquid level, an automatic tank thermometer (ATT) to measure the oil temperature, and one or more pressure sensors to measure the liquid static pressure, for measurement (3.1).
• The measurement data are used together with the tank capacity table and petroleum measurement tables to provide liquid level, temperature, mass, metered volume and standard volume, as well as metered density and standard density (3.1 Note).
• The hybrid processor uses the liquid level, temperature and pressure data measured by HTMS, combined with tank parameters, to calculate density, volume and mass (3.2).
• The hybrid method for calculating density is based on pressure balance: the pressure increment between any two points is independent of the path by which it increases (A.3).
• For a summary of calculations, see Annex A (informative annex); for measurement accuracy and uncertainty analysis, see Annex B (informative annex).

4. Reagents and materials (purity / preparation)

not provided in the available source (this standard is a method standard for system selection, installation, calibration and verification, and does not include clauses on reagents and materials).

5. Instruments and equipment

• Main components of the system (5.1): automatic level gauge (ALG), automatic tank thermometer (ATT), one or more pressure sensors, and a hybrid processor that stores tank parameters and performs calculations.
• Automatic level gauge (ALG) (5.2): selected according to the intended use in HTMS; selected and installed according to ISO 4266-1; for HTMS based on mass custody transfer, the minimum accuracy of ALG shall comply with Table 1.
• Pressure sensor (5.3): selected according to the uncertainty calculation in the actual application (see Clause 6 and Annex B); installation shall comply with the relevant provisions of GB/T 18273; pressure sensors used for atmospheric storage tanks should be gauge pressure transmitters (one port open to the atmosphere); the use of electronic analog output or digital output depends on the total accuracy requirement for the pressure sensor in the intended use.
• Automatic tank thermometer (ATT) (5.4): selected and installed according to GB/T 21451.4; for HTMS based on mass custody transfer, the minimum accuracy of ATT shall comply with Table 3; it may be an average ATT or a single-point temperature sensor; if multiple elements are present and the oil vapor temperature can be independently measured by an unimmersed element, ATT may be used to calculate the oil vapor density.
• Hybrid processor (5.5): it may be implemented by a locally installed microprocessor, a remote computer, or the user's computer system; it may be dedicated to one tank or shared among several tanks; it may perform linearization and/or temperature compensation correction for various HTMS components; all measured and calculated variables shall be capable of being displayed, printed, or transmitted to other processors.
• Optional sensors (5.6): a middle transmitter (P.) can calculate an alternative density for comparison or warning purposes (HTG), and can also be used for calculation of a backup density when ALG cannot be used (for details see GB/T 18273); means for determining atmospheric density (5.6.2).

Table 1 Maximum permissible error of ALG

Table 2 Maximum permissible error of pressure sensors

Table 3 Maximum permissible error of ATT

Table 4 Typical HTMS parameters (parameter groups and parameters)

• Tank data: roof type (fixed roof, external floating roof or internal floating roof), floating roof (deck) mass (only for floating roof tanks), critical zone height (only for floating roof tanks), leg height (only for floating roof tanks), shell type (insulated or non-insulated), shell material (coefficient of thermal expansion), tank capacity table (volume at specified liquid level), tank calibration temperature (temperature to which the tank capacity table is corrected), liquid level hmin (for all tanks, see 6.2), liquid level h. (distance from the hybrid method reference point to the datum plate (point))
• Data for ALG components: reference height (vertical distance from the datum plate (point) to ALG), sensor configuration (a tank may have one or more sensors), sensor position hb (height relative to the hybrid method reference point, see Figure A.1), height of sensor P (can be programmed in ALG)
• Pressure sensor data: type of ATT (resistive or other means, can be programmed in ALG)
• Data for ATT components: element type, number of elements, vertical position of elements
• Oil data: petroleum measurement table corresponding to the stored product (for details see GB/T 1885), vapor parameters, free water level
• Measurement data: actual height, ullage
• Environmental data: local gravitational acceleration (obtained from an authoritative body), ambient temperature (optional), ambient pressure (optional) (Note: Table 4 source-text extraction has serialization issues, and the correspondence between groups and parameters requires confirmation (source-text extraction))

6. Recommended operating conditions

• The measurement and calculation of HTMS are defined as two modes (Mode 1 and Mode 2), to be selected by the user according to the purpose of use and oil characteristics (7.1).
• HTMS Mode 1 (7.2): it is the best choice when the main concern is standard volume and the oil density remains relatively consistent at low liquid levels. When the liquid level is above a predetermined level (hmin), the average density of the liquid in the tank is continuously calculated; when the liquid level is below hmin, the last calculated standard density when the liquid level dropped to hmin is used (Dret); alternatively, when the liquid level is below hmin, if the oil is stratified or new oil enters the tank, Dret may be manually entered. Table 5 (Method A) and Table 6 (Method B) respectively specify the measurement and calculation methods required for Mode 1 when the liquid level is above hmin and below hmin.
• HTMS mode 2 (7.3): it is the best choice when the main concern is that the output value is oil product quality; when standard volume is the main output value and the user expects that at low liquid levels the stored standard density (mode 1) does not represent the actual standard density (caused by stratification or the introduction of a new oil product), mode 2 is also the best choice. Mode 2 does not use hmin or the saved oil product density; at all liquid levels above P, the standard density is calculated (D.); a “P disconnect liquid level” is introduced, and when the oil product is at or below the disconnect liquid level, the last calculated D.d is used and remains unchanged; above this liquid level, all measurements and calculations are performed according to method A (table 5), and below it, measurements and calculations are performed according to method B (table 6).
• Figure 1: a simplified diagram of the calculation methods for HTMS liquid-level-related mode 1 and mode 2 (including the positions of hmin and P, the P disconnect position, and the datum plate).

Table 5 Summary of measured data and calculated data for HTMS—calculation method A

Table 6 Summary of measured data and calculated data for HTMS—calculation method B

7. Sampling and sample preparation

• Density comparison sampling: carried out according to GB/T 4756 (8.5.2.2, 9.4.1.2).
• Density determination: carried out according to GB/T 1884 or SH/T 0604 (8.5.2.2, 9.4.1.2).
• Density comparison liquid level: when HTMS provides online measured density (that is, the liquid level is above hmin), the density comparison should be carried out at a liquid level approximately (4±0.5) m above P (8.5.2.2); periodic density comparison inspection is carried out at the (4±0.5) m liquid level and when HTMS can measure density online (that is, the liquid level is above hmin) (9.4.1.2).
• Other sampling and sample preparation clauses: not provided in the available source.

8. Analysis procedure

• Initial preparation (8.2): confirmation of the tank capacity table (8.2.1); establishment of the mixing method reference point (8.2.2); parameter input for HTMS (8.2.3).
• Initial calibration (8.3): overview (8.3.1, each component should be calibrated separately, for example, data derived from a pressure sensor should not be used to calibrate ALG, and vice versa); calibration of ALG (8.3.2, on-site calibration according to GB/T 21451.1 or ISO 4266-1, meeting the tolerance in Table 1); calibration and zero adjustment of the pressure sensor (8.3.3, usually calibrated by the manufacturer; after installation, calibration should be checked using an accurate pressure calibrator traceable to the national standard, and if out of tolerance it should be replaced; zero adjustment should use the method given in GB/T 18273); calibration of ATT (8.3.4, calibrated according to GB/T 21451.4, meeting the tolerance in Table 3).
• Verification of the calculation results of the mixing processor (8.4): using suitable verification data, check the calculation results of the mixing processor by manual calculation, and the two should be consistent with each other.
• Initial on-site inspection (8.5): overview (8.5.1); initial on-site inspection based on volume metering (8.5.2); initial on-site inspection based on mass metering (8.5.3).
• Initial on-site inspection based on volume (8.5.2.1): a) ALG inspected according to the procedure and tolerance of ISO 4266-1; b) ATT inspected according to the procedure and tolerance of GB/T 21451.4; c) the pressure sensor (and also the transmitter if the pressure sensor and transmitter are independent of each other) should be subjected to on-site zeroing and linearity inspection: 1) for zero adjustment, the connecting line between the pressure transmitter and the oil tank should be disconnected, and its pressure introduction port should be open to the atmosphere; after adjustment, the zero error should be approximately zero; 2) use a high-precision pressure standard traceable to the national standard to inspect linearity; the linearity inspection should be carried out at at least two test pressures of approximately 50% and 100% in the pressure range; the relative linearity error is given by calculating the deviation between the pressure sensor indication (minus the observed zero error) and the pressure standard; the linearity error at any test pressure should not exceed the maximum linearity error given in Table 2; 3) after completing zeroing and linearity inspection, a final check should be carried out to determine whether the zero error remains within the accuracy given in Table 2; the residual zero reading and linearity error should be recorded as documentation.
• Density comparison based on volume (8.5.2.2): the standard density determined by HTMS should be compared with the average oil product density determined from a representative sample in the tank that has been inspected; the difference between the oil product density determined by HTMS and the density of the tank sample should be within ±0.5% of the density reading; if the oil product in the tank is uniform, a stricter tolerance (less than ±0.5% of the reading) may be used, and this tolerance may be established using statistical quality control methods.
• Initial on-site inspection based on mass (8.5.3.1): a) ALG inspected according to the procedure of ISO 4266-1, and the tolerance may be relaxed to 12 mm; b) ATT inspected according to the procedure and tolerance of GB/T 21451.4, and the tolerance may be relaxed to 1 ℃; c) the pressure sensor (and also the transmitter if the pressure sensor and pressure transmitter are independent devices) affects the accuracy of mass measurement, and zeroing should be carried out and measurement should be carried out using a suitable pressure standard traceable to the national standard (for example, a handheld terminal or an accurate pressure calibrator) to determine whether the sensor/transmitter remains within the accuracy given in Table 2.
• Density inspection based on mass (8.5.3.2): inspect the measured density of HTMS according to the method given in 8.5.2.2.
• Mass metering accuracy inspection based on mass (8.5.3.3): the inspection should be carried out using the method specified in GB/T 18273; the accuracy given in GB/T 18273 is “transfer accuracy”, and the inspection involves the amount of liquid input to or output from the oil tank.
• Periodic inspection (Chapter 9): overview (9.1, the HTMS used for custody transfer metering should also undergo periodic on-site inspection after completion of commissioning and initial on-site inspection, also called “confirmation”); purpose (9.2); adjustment during periodic inspection (9.3); periodic inspection based on volume custody transfer (9.4); periodic inspection based on mass custody transfer (9.5); handling of out-of-tolerance during periodic inspection for HTMS used for custody transfer metering (9.6).
• Purpose of periodic inspection (9.2): a) ensure that the performance of HTMS remains within the required accuracy range; b) as long as the parties to the custody transfer can accept it, allow the use of statistical quality control methods to establish the frequency of repeat calibration.
• Adjustment during periodic inspection (9.3): if the inspection process confirms that the performance change of HTMS exceeds the predetermined range, recalibration and/or readjustment should be carried out; otherwise, no adjustment should be made during the inspection process; this range should take into account the expected combined measurement uncertainty of HTMS, the standard equipment, and the performance requirements of HTMS.
• Periodic inspection based on volumetric transfer (9.4.1.1): a) ALG shall be inspected according to the periodic inspection methods and tolerances given in ISO 4266-1 (for vertical cylindrical tanks); b) ATT shall be inspected according to the periodic inspection methods and tolerances given in GB/T 21451.4 (for vertical cylindrical tanks); c) Pressure sensor/transmitter stability inspection: 1) Inspect the transmitter zero on site; the zero reading ("existing") value shall not exceed the manufacturer's specified value or the maximum recommended value of the zero error given in Table 2; if the zero reading is greater than the maximum recommended value given in Table 2 and does not exceed the manufacturer's specified value, the transmitter shall be zeroed or zero software correction shall be performed; the zero reading "existing" value and "residual" value shall be recorded as documentation; if it exceeds the manufacturer's specified value, the manufacturer shall be consulted; 2) Use a high-precision pressure calibrator traceable to national standards to inspect the transmitter linearity on site; the linearity error shall not exceed the manufacturer's specified value or the maximum recommended value given in Table 2; if it exceeds the manufacturer's specified value, the manufacturer shall be consulted; the linearity reading "existing" value and "residual" value shall be recorded as documentation.
• Periodic inspection density comparison based on volumetric transfer (9.4.1.2): The oil density measured by HTMS shall be compared with the product density measured by experimental analysis of a representative tank sample; sampling according to GB/T 4756, density determination according to GB/T 1884 or SH/T 0604; the density comparison shall be performed at the liquid level of (4±0.5) m and when HTMS can measure density online (i.e., the liquid level is above hmin); the difference between the oil density measured by HTMS and the tank sample density shall be within ±0.5% of the density reading; if the product in the tank is uniform, a stricter tolerance (less than ±0.5% of the reading) may be used, and this tolerance may be established using statistical quality control methods.
• Periodic inspection frequency (9.4.2.1): a) ALG shall be inspected according to the frequency for periodic on-site inspection given in ISO 4266-1, once a month when initially put into use; when performance remains stable within the inspection tolerance for six consecutive months, the inspection interval may be extended to once every three months; b) ATT shall be inspected according to the frequency for periodic on-site inspection given in GB/T 21451.4; newly installed or repaired ATT shall be inspected once every three months; if the performance of ATT is stable, the inspection frequency may be reduced to once a year; c) For pressure sensors, the zero stability and linearity stability of the pressure sensor/transmitter shall be inspected at least once a year according to the initial inspection procedure.
• Periodic inspection density comparison frequency (9.4.2.2): Using the method specified in 9.4.1.2, the product density comparison shall be performed at least once every three months according to the initial inspection procedure.
• Periodic inspection based on mass transfer (9.5.1.1): a) ALG shall be inspected according to the periodic calibration inspection procedure given in ISO 4266-1, and shall meet the tolerances specified in Table 1; b) ATT shall be inspected according to the periodic calibration inspection procedure given in GB/T 21451.4, and shall meet the tolerances specified in Table 3; c) The stability of the zero and linearity of the pressure sensor/transmitter shall be inspected according to the method given in 9.4.1.1c), and shall meet the tolerances given in Table 2.
• Periodic inspection density comparison based on mass transfer (9.5.1.2): In mass-based transfer metering, the comparison of the product density measured by HTMS with the product density determined by the manual method is not mandatory; if required, such comparison shall be performed according to 9.4.1.2.
• Periodic inspection frequency based on mass transfer (9.5.2): a) Newly installed or repaired ALG shall be inspected once every three months; if the performance of ALG is stable, the inspection frequency may be reduced to once every six months; however, density comparison shall be performed once every three months, and statistical data show that the entire system is stable; b) Newly installed or repaired ATT shall be inspected at a frequency consistent with ALG; c) The zero and linearity stability of the pressure sensor/transmitter shall be inspected quarterly according to the initial inspection procedure; if the linearity of the pressure sensor/transmitter is stable, the frequency of linearity inspection may be reduced to once every six months; the comparison of the product density measured by HTMS with the density determined by the manual method is not mandatory; in addition, if the density comparison is used as the basis for reducing the frequency of periodic inspection of ALG [9.5.2a)], the density comparison shall be performed at least quarterly.
• Out-of-tolerance handling (9.6): 9.6.1 During periodic on-site inspection, if a component of HTMS is found to be out of tolerance, the cause shall be identified to determine whether the component needs adjustment, calibration, resetting, or repair; 9.6.2 After adjustment or repair, the corresponding component shall be re-inspected using the procedure specified in 8.5.

9. Qualitative and Quantitative and Calculation Formulas

• Gross metered volume (A.2): GOV=[(TOV−FW)×CTSh]−FRV
  • TOV: The total metered volume calculated from ALG and the tank capacity table; FW: The volume of free water; FRV: For floating roof tanks, the displaced liquid volume when the liquid level is above the floating height.
  • FRV=FRW/[(D.h 1.1)×VCF] (source-text extraction doubtful point, requires confirmation against the source standard (source-text extraction))
    • FRW: The apparent mass (weight) of the floating roof; Drk: The standard density of the oil; VCF: The volume correction factor obtained from the petroleum measurement table based on the standard density and metering temperature; CTSh: The correction value for thermal expansion of the tank wall.
  • CTSh=1+2a(Lt)+Q"(At) (source-text extraction doubtful point, requires confirmation against the source standard (source-text extraction))
    • a: The linear expansion coefficient given in Table A.2; Note: The last term in the calculation formula of CTSh has very little effect on the calculation result and can be ignored.
  • At=tb−t(source-text extraction doubtful point, requires confirmation against the source standard (source-text extraction))
    • tsn: Tank wall temperature (determined according to GB/T 19779); t: The calibration temperature of the tank capacity table (the tank wall temperature set when compiling the tank capacity table, which is usually 20 ℃ in our country).
• Table A.2 Linear expansion coefficient

  Tank wall material	a/℃⁻¹
  Low carbon steel	0.000 011 2
  304 stainless steel	0.000 0173
  316 stainless steel	0.000 0159
  17-4PH stainless steel	0.000 0108

• Oil metering density (in vacuum) (A.3): The basis for calculating density by the hybrid method is pressure balance; the value of Dob can be calculated by the following formula (formula source-text extraction incomplete, requires confirmation against the source standard (source-text extraction)):
  • Liquid head ≈ g×(L−Z)Dote (at position P)
  • Ambient air head ≈ ×h. D. (at position P)
  • Symbols: Dobe— metering density of the liquid in vacuum; N— unit constant (see Table A.1); L—ALG liquid level (actual height) reading; Z—hs+h. (root height from transmitter P to the tank datum plate, see Figure A.1); h— vertical distance from the hybrid method reference point to the pressure center of sensor P; h. — vertical distance from the tank datum plate to the hybrid method reference point; g— local gravitational acceleration; h— vertical distance between the force centers of the diaphragms of sensors P and P; Dy— vapor density inside the tank; D.— ambient air density. Note: If the hybrid method reference point is at the same height as the tank datum plate, h. = 0.
• Mass of oil in vacuum (A.4): m, =GOV×Dobs
  • my: Mass of oil in vacuum; GOV: Gross metered volume calculated in A.2; Dobs: Oil metering density (in vacuum) calculated in A.3. Note: For atmospheric storage tanks, m** can be assumed to be zero.
• Apparent mass of oil in air (A.5): m. =m, ×(1−D, /Dat) (source-text extraction doubtful point, requires confirmation against the source standard (source-text extraction))
  • Apparent mass of oil in air; m.: Mass of oil in vacuum calculated in A.4; D.: Ambient air density (when direct measurement is not possible, air density is calculated according to 1.1 kg/m³); Do: Liquid metering density (in vacuum) calculated in A.3.
• Gross standard volume (A.6): GSV=GOV×VCF
  • GOV: Gross metered volume calculated in A.2; VCF: Volume correction factor usually obtained from GB/T 1885.
• Table A.1 Formula unit table for HTMS (constants and units, source-text extraction serial, requires confirmation against the source standard (source-text extraction)): N metering pressure 1.000 Pa / 1000.0 kPa / 100.Q mbar / 100 000 bar; tank capacity table volume m³; local gravitational acceleration m/s²; liquid level m; metering volume and standard volume m³; metering density and mass kg/m³; standard density kg/m³; mass kg.
• Appendix B (Informative Appendix) Measurement Accuracy and Uncertainty Analysis: B.1 Overview (symbols, definitions, and units); B.2 Uncertainty of metering density; B.3 Uncertainty of mass; B.4 Uncertainty of standard volume; B.5 Tank structural coefficient; B.6 Determination of hmin; B.7 Influence of density uncertainty on volume correction factor (VCF).
• B.2 Uncertainty of metering density (formula source-text extraction incomplete, requires confirmation against the source standard (source-text extraction)):
  • UD=…; Uptowl=Up-ano+ Lg(L−Z)(D−Dy)+Pamax]×Up-tneaty; U Ps-toual=UPaaeto+pimex×UP linearity.
• B.3 Uncertainty of mass (formula source-text extraction incomplete, requires confirmation against the source standard (source-text extraction)):
  • Up-toual=UPl arro t piapeled×Upi-lleaniy; Piappled=Fg ("S Z) D+g_h, −(L−2)" Dy ten psmu gh,D, ~g (L Z) (D D) + pmax; UPl-toal=Upl-aem+ [g (L−Z) (D Dy) + Pame] × UPi-lineaaty; Uptoul=Upaen Pamsx × Ups-lineais.
• B.4 Uncertainty of the standard volume (formula source-text extraction incomplete, requires confirmation against the source standard (source-text extraction)).
• B.5 Tank structural coefficient: B.5.1 vertical cylindrical tank Fa=1.0; B.5.2 spherical tank (d, is the inner diameter) Fa=… (formula source-text extraction incomplete, requires confirmation against the source standard (source-text extraction)); B.5.3 horizontal cylindrical tank (d is the inner diameter) Fo=… (formula source-text extraction incomplete, requires confirmation against the source standard (source-text extraction)).
• B.6 Determination of hmin: defined constant A=UPi am+Pamx × Upi-lineaniy; hmin is calculated by the following formula: 8 × [DXU." (D D,) ? × UP.lineatty?] (formula source-text extraction incomplete, requires confirmation against the source standard (source-text extraction)).
• B.7 Influence of density uncertainty on VCF: Table B.9 Example of the influence of crude oil density uncertainty on the volume correction factor (basis: oil temperature = 20 ℃, "true" standard density is 885 kg/m³, volume correction factor table: ISO 91-1:1992, Table 54A); Table B.10 Example of the influence of petroleum product density uncertainty on the volume correction factor (basis: oil temperature = 20 ℃, "true" density is 745 kg/m³, volume correction factor table: ISO 91-1:1992, Table 54B).

10. Precision

• This standard does not give repeatability/reproducibility values in a "precision" clause; the relevant precision and uncertainty analysis is given in Chapter 6 and Appendix B (informative appendix).
• Density comparison tolerance: the difference between the oil density measured by HTMS and the density of the tank sample shall be within ±0.5% of the density reading; if the oil in the tank is uniform, a stricter tolerance (less than ±0.5% of the reading) may be used, and this tolerance may be established using statistical quality control methods (8.5.2.2, 9.4.1.2).
• Appendix B gives calculation examples for metering density, mass, and standard volume uncertainty (Tables B.1 to B.6) and calculation examples for hmin (Tables B.7, B.8).
• Table B.1 Example of metering density uncertainty—floating roof tank (product: gasoline in a floating roof tank; D=741.0 kg/m³, Dy=1.2 kg/m³, Z=0.2 m, g=9.81 m/s²): P zero point error Case 1 50 Pa / Case 2 100 Pa / Case 3 50 Pa; linearity error 0.000 7 / 0.001 0 / 0.000 7 (percentage of reading); UL 0.004 m / 0.004 m / 0.012 m; Uz 0.003 m / 0.003 m / 0.003 m; uncertainty of metering density for vertical cylindrical tank [±% of reading]: L=4 m 0.283 / 0.480 / 0.411; L=10 m 0.149 / 0.246 / 0.188; L=16 m 0.118 / 0.190 / 0.138.
• Table B.2 Example of metering density uncertainty—fixed roof tank (product: diesel (or mixed oil) in fixed roof atmospheric tanks of various structures; D=842.9 kg/m³, Dv=1.2 kg/m³, Z=0.2 m, g=9.81 m/s², p3m=5 000 Pa): P. zero point error 50/100/50 Pa; P. linearity error 0.000 7/0.001 0/0.000 7; P zero point error 24/40/24 Pa; P linearity error 0.002/0.005/0.002; UL 0.004/0.004/0.012 m; Uz 0.003/0.003/0.003 m; vertical cylindrical tank L=4 m 0.294/0.498/0.418; L=10 m 0.151/0.248/0.190; L=16 m 0.118/0.190/0.138; spherical tank diameter = 20 m L=4 m 0.294/0.498/0.418; L=10 m 0.151/0.248/0.190; L=16 m 0.118/0.190/0.138; horizontal cylindrical tank L=1 m 1.194/2.050/1.849; L=2 m 0.560/0.957/0.841; L=3.5 m 0.330/0.561/0.476.
• Table B.3 Example of mass metering uncertainty—floating roof tank (product: gasoline in a floating roof tank; D=741.0 kg/m³, D=1, Z=0.2 m, g=9.81 m/s²): P. zero point error 50/100/50 Pa; linearity error 0.000 7/0.001 0/0.000 7; UL 0.004 m; Uz 0.003 m; UAE percentage uncertainty 0.001; uncertainty of mass metering for vertical cylindrical tank [±% of reading]: L=4 m 0.281/0.479/0.282; L=10 m 0.175/0.262/0.175; L=16 m 0.152/0.213/0.152.
• Table B.4 Example of mass metering uncertainty—fixed roof tank (product: diesel (or mixed oil) in fixed roof atmospheric tanks of various structures; D=842.9 kg/m³, Dw=1.2 kg/m³, Z=0.2 m, g=9.81 m/s², Psmx=5 000 Pa): P zero point error 50/100/50 Pa; linearity error 0.000 7/0.001 0/0.000 7; P zero point error 24/40/24 Pa; linearity error 0.002/0.005/0.002; UL 0.004 m; Uz 0.003 m; UAE 0.001; uncertainty of mass metering [±% of reading]: vertical cylindrical tank L=4 m 0.293/0.497/0.303; L=10 m 0.177/0.265/0.178; L=16 m 0.153/0.213/0.153; spherical tank diameter = 20 m L=4 m 0.293/0.501/0.377; L=10 m 0.177/0.265/0.186; L=16 m 0.153/0.213/0.153; horizontal cylindrical tank diameter = 4 m L=1 m 1.091/1.992/1.106; L=2 m 0.524/0.937/0.533; L=3.5 m 0.325/0.557/0.336.
• Table B.5 Example of standard volume metering uncertainty—floating roof tank (product: gasoline in a floating roof tank; td=15 ℃, t=25 ℃, Dis=750 kg/m³; K. = 346.4228/℃, K, = 0.438 8