GB/T 1885-1998 Petroleum measurement tables

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Card type: Test method

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

• Standard number: GB/T 1885—1998
• Chinese name: Petroleum measurement tables
• English name: Petroleum measurement tables
• Replacement relationship: replaces GB/T 1885—83 (91); from the date of implementation it simultaneously replaces GB/T 1885—83 (91)
• Adoption relationship: equivalent adoption of ISO 91-2:1991 "Petroleum measurement tables—Part 2: Tables based on a reference temperature of 20℃", the calculation results are consistent with ISO 91-2:1991
• Issued/implemented: approved by the State Bureau of Quality and Technical Supervision 1998-06-17, implemented on 1999-03-01
• Responsible body: Research Institute of Petroleum Processing, China Petrochemical Corporation
• Drafting organization: Research Institute of Petroleum Processing, China Petrochemical Corporation
• Main drafters: Wei Jinxiang, Yang Tianfu, Guan Huanzheng
• First issued: first issued in 1980 year 4 month, revised in 1983 year 12 month, review confirmed in 1991 year

2. Scope of application and non-applicability

• This standard specifies the method for converting glass petroleum hydrometer readings (apparent density) obtained at non-standard temperatures to density at standard temperature (standard density) and volume correction factors.
• Applicable to crude oil, lubricating oils and other liquid petroleum products.
• The standard temperature specified in this standard is 20℃.
• The thermal expansion data of oils used in compiling the petroleum measurement tables in this standard are consistent with ISO 91-1.
• Not applicable: no explicit non-applicability clause is provided in the available source.

3. Method principle

• Through the petroleum measurement tables (standard density table, volume correction factor table), the apparent density measured by a glass petroleum hydrometer at a non-standard temperature is converted to the standard density at the standard temperature 20℃, and the volume correction factor (VCF) is found from the standard density and the metering temperature.
• Definition of volume correction factor: the ratio of the volume of petroleum at the standard temperature to its volume at a non-standard temperature.
• When compiling the petroleum measurement tables, the glass thermal expansion coefficient used for correcting the hydrometer reading is consistent with ISO 91-1, both being 23×10⁻⁶℃⁻¹, slightly lower than the conventional value cited in ISO 1768 (25×10⁻⁶℃⁻¹). If both trading parties consider that this error effect should be taken into account, then before looking up the standard density table, 0.000002ρ′(t−20) may be subtracted from the hydrometer reading, where ρ′ is the glass hydrometer reading and t is the test temperature.
• Annex B gives a simplified flow diagram for the calculation of petroleum measurement tables (calculation flow for standard density of crude oil, lubricating oils and other petroleum products; the dashed box contains the calculation flow for volume correction factors of crude oil, lubricating oils and other petroleum products; the large solid-line box on the right is only used for the calculation of density in the linear region 15℃ of other petroleum products).

4. Reagents and materials (purity / preparation)

Not provided in the available source.

5. Instruments and equipment

Not provided in the available source (the method involves glass petroleum hydrometer readings; density determination is in accordance with GB/T 1884).

6. Recommended operating conditions

• Standard temperature: 20℃.
• Temperature values for table lookup are not interpolated; only the closer temperature value is used for table lookup.
• Standard density table: if the known apparent density value lies exactly between two adjacent apparent density values in the apparent density column, interpolation may be used to determine the standard density, but temperature values are not interpolated.
• Volume correction factor table: if the known standard density lies between two adjacent standard densities in the standard density row, interpolation is not necessary; only the volume correction factor corresponding to the closer standard density value is taken. Temperature values are not interpolated; only the closer temperature value is used for table lookup.
• Unit conversion: when the apparent density uses the fractional units g/cm³ and kg/L, before table lookup it should first be multiplied by 10³ to convert the unit to kg/m³.

7. Sampling and sample preparation

Not provided in the available source.

8. Analysis procedure

8.1 Use of the standard density table

Steps for converting the apparent density of a certain oil product at a certain test temperature (in accordance with GB/T 1884) to standard density: a) Select the standard density table for the corresponding oil product according to the oil product category; b) Determine the density interval in the standard density table where the apparent density lies; c) In the apparent density column, find the known apparent density value; in the temperature column, find the known test temperature value. The intersection of this apparent density value and test temperature value is the standard density of the oil product. If the known apparent density value lies exactly between two adjacent apparent density values in the apparent density column, interpolation may be used to determine the standard density, but temperature values are not interpolated; use the closer temperature value for table lookup.

8.2 Use of the volume correction factor table

Steps for converting the known standard density of an oil product to the volume correction factor for correcting the volume at the metering temperature to standard volume: a) Select the volume correction factor table for the corresponding oil product according to the oil product category; b) Determine the density interval in the volume correction factor table where the standard density lies; c) In the standard density column, find the known standard density value; in the temperature column, find the metering temperature value of the oil product; the intersection of the two is the volume correction factor for correcting the oil product from the metering temperature to the standard temperature. If the known standard density lies between two adjacent standard densities in the standard density row, interpolation is not necessary; only the volume correction factor corresponding to the closer standard density value is taken. Temperature values are not interpolated; only the closer temperature value is used for table lookup.

8.3 Unit conversion

When the apparent density uses the fractional units g/cm³ and kg/L, before table lookup it should first be multiplied by 10³ to convert the unit to kg/m³.

9. Qualitative and quantitative and calculation formulas

9.1 Definitions (Chapter 3)

• 3.1 Test temperature (t): the temperature of the liquid sample when the hydrometer reading is taken, ℃.
• 3.2 Apparent density (ρ′): the reading of the glass hydrometer in the liquid sample at the test temperature, kg/m³ or g/cm³.
• 3.3 Standard density (ρ20): the density at the standard temperature 20℃, kg/m³.
• 3.4 Metering temperature (t): the temperature of the oil product in the storage container or pipeline at the time of metering, ℃.
• 3.5 Standard volume (V20): the volume at the standard temperature 20℃, m³.
• 3.6 Volume correction factor (VCF): the ratio of the volume of petroleum at the standard temperature to its volume at a non-standard temperature.

9.2 Interpolation calculation (Example 2)

From table lookup at 40℃ temperature, the standard density corresponding to an apparent density of 804.0 kg/m³ is 818.7 kg/m³; at the same temperature, the standard density corresponding to an apparent density of 806.0 kg/m³ is 820.6 kg/m³. Using interpolation, the change in standard density corresponding to an apparent density change of 1.0 kg/m³ is (820.6−818.7)/(806.0−804.0)=0.95, from which the standard density of this crude oil is obtained as 818.7+ (805.7−804.0)×0.95=820.3 kg/m³.

9.3 Glass hydrometer correction term (Note)

If both trading parties consider that this error effect should be taken into account, then before looking up the standard density table, 0.000002ρ′(t−20) may be subtracted from the hydrometer reading, where ρ′ is the glass hydrometer reading and t is the test temperature.

10. Precision

Not provided in the available source.

11. Report

Not provided in the available source.

12. Referenced documents

• GB/T 1884 Petroleum and liquid petroleum products—Determination of density (hydrometer method)
• ISO 91-1 Petroleum measurement tables—Part 1: Tables based on reference temperatures of 15℃ and 60°F
• ISO 1768 Glass hydrometers—Conventional value for the coefficient of volumetric thermal expansion (for use in compiling liquid measurement tables)
• ISO 91-2:1991 Petroleum measurement tables—Part 2: Tables based on a reference temperature of 20℃

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick reference Q&A