GB/T 9109.5-2025Dynamic measurement of petroleum and liquid petroleum products — Part 5: Calculation of oil quantities (English PDF)

3.1 Terms and definitions

3.1.1 Indicated volume or mass

During measurement, the oil value displayed by the flowmeter counter or other display unit, including water and sediment transported through the flowmeter.

3.1.2 Total observed volume or mass

The indicated volume or mass as multiplied by the flowmeter factor corresponding to the oil product and its flow rate. This value is not corrected for temperature and pressure.

3.2 Symbols

See Table 1.

4.1 Effective digits of measurement parameters

4.1.1 Depending on the density reading and density conversion, keep 1 decimal place,

that is, 0.1 kg/m3.

4.1.2 Measurement of moisture content in oil (distillation method), round to two

decimal places 0.01%.

4.2 Numerical rounding off

4.2.1 The numerical rounding off method shall comply with the provisions of GB/T

8170 In most cases, the number of decimal places used is affected by the data source.

In the absence of other limiting factors, rounding off shall be performed, according to the decimal places specified in Table 2.

4.2.2 MF, Ctl, Cpl, Csw, Fa shall be rounded to the fourth decimal place, in accordance with the provisions of GB/T 8170.

4.2.3 The oil quantity settlement value follows the requirements of GB/T 8170; the

volume value is rounded to 0.001 m3; the mass value is rounded to 0.001 t. Example.

5.1 Overview

In order to obtain accurate results of the oil quantity (volume or mass), which is measured by the flowmeter, it shall first ensure that the basic data for calculating the oil quantity (such as the indicated volume of the flowmeter, measuring temperature, measuring pressure, density, moisture content, etc.) are obtained, in accordance with the standard method (or procedure) (see Appendix A);

5.2 Flowmeter

The accuracy level of flowmeters, which are used for trade transfer measurement, shall be no less than level 0.2.

5.3 Measuring temperature

The measurement temperature of oil products shall be measured or recorded, using a mercury-in-glass thermometer, which has a graduation value of not less than 0.2 °C, OR other types of temperature transmitters, which are not lower than the same accuracy requirements.

5.4 Measuring pressure

Oil measuring pressure shall be measured or recorded, using a 0.4 grade pressure gauge or other types of pressure transmitters, which are not lower than the same accuracy requirements.

5.5 Sampling

Oil sampling shall be carried out, in accordance with the requirements specified in GB/T 4756 or GB/T 27867.

5.6 Density

5.7 Moisture content

It is measured according to GB/T 8929; it can also be measured according to GB/T 260 and GB/T 6531.

6.1 Method overview

6.1.1 The settlement basis for oil trade is divided into weight or volume in the air.

Therefore, oil quantity calculation is also divided into two methods.

6.1.3 Taking the volume-weight method as an example (flowmeter factor method),

during the measurement period, record the indicated volume (Vt),

6.2 Volume settlement

6.2.1 Calculation formula

6.2.2 Calculation steps

6.2.2.1 Determine Vt

The indicated volume, which is measured by the flowmeter under measuring pressure, is calculated according to formula (4).

If the flowmeter uses K factor, the indicated volume, which is measured by the flowmeter under metering pressure, is calculated according to formula (5).

6.2.2.4 Determine Cpl

If the reading of the flowmeter has been corrected by pressure compensation, OR the impact at low pressure is less than 0.01%, then set Cpl = 1 0000; otherwise, calculate it according to formula (6).

6.2.2.6 Determine Vsw

Vsw is calculated according to formula (8).

6.2.2.7 Calculation formula of mass flowmeter volume

Vgs is calculated according to formula (9).

6.3 Settlement based on weight in air

It is divided into three types according to the measurement method. One is a flowmeter based on volume measurement coupled with a glass float meter.

6.3.1 Measurement method of flowmeter coupled with glass float meter

6.3.2 Measurement method of flowmeter with online density meter

6.3.3 Mass flowmeter measurement method

6.3.3.2 Calculation steps

6.3.4 Calculation formula of oil moisture content

msw is calculated according to formula (26).

7.1 Measurement data requirements

7.1.1 Use standardized conditions and prescribed calculation procedures, to obtain

consistent calculation results from the same set of oil quantity data; standardize the calculation rules for oil quantity (volume or mass).

7.1.3 Ensure that copies of measurement bills (including faxes) are clearly written,

unless the relevant parties agree to make modification or deletion on the measurement bills.

7.1.4 If there is an error in the measurement bill, the bill shall be marked "invalid" and a new bill shall be prepared.

7.3 Format and content of measurement bills

Please refer to Appendix F for the format and content of the measurement bill.

8.1 Calculation of standard volume of oil products

8.1.2 Calculation of oil quantity using basic error method

According to formula (1), calculate the net standard volume of oil.

8.1.3 Calculation of oil quantity using flowmeter factor method

8.2 Calculation of oil quality and weight in air

8.2.1 Measurement example

For continuous measurement of long-distance crude oil pipelines, a flowmeter with a glass float meter is used to manually measure the density; meanwhile the flowmeter factor is used, to calculate the weight of oil in the air. The measured values of the metrological parameters are as shown in Table 7.

8.2.4 Temperature correction factor Ctl

From t = 37.75 °C and rho20 = 845.3 kg/m3, see Table 8.

8.2.5 Pressure correction factor Cpl

8.4 Calculation of oil products measured using K factor method

Diesel at a metering station is measured using a turbine flowmeter. The measured values and calculation procedures of the measurement parameters are as shown in Table 11.

8.4.5 Deduction of moisture content

The measured oil is trade transfer oil, so the moisture content shall be deducted.

8.4.6 Calculation of volume under different standard reference conditions

8.4.6.3 Volume calculation at 60 °F and 101.325 kPa

The original measurement data and measurement procedures are as shown in Table 14. ......