NB/SH/T 0248-2019 Determination of cold filter plugging point of diesel and domestic heating oils

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Card type: Test method

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

• Standard number: NB/SH/T 0248—2019
• Chinese full title: Determination of cold filter plugging point of diesel and domestic heating oils
• English name: Diesel and domestic heating fuels—Determination of cold filter plugging point
• Replacement relationship: replaces SH/T 0248—2006; previous versions are SH/T 0248—1992, SH/T 0248—2006
• Adoption relationship: modified adoption by redrafting method of British Energy Institute standard IP 309/16 "Diesel and domestic heating oils—Determination of cold filter plugging point—Stepwise cooling bath method"
• Publication/implementation: published on 2019-11-04, implemented on 2020-05-01
• Issuing authority: National Energy Administration
• Technical committee: Subcommittee on Petroleum Fuels and Lubricants of the National Technical Committee for Standardization of Petroleum Products and Lubricants (SAC/TC280/SC1)
• Drafting organization: Sinopec Research Institute of Petroleum Processing

2. Scope of application and non-applicability

• This standard specifies methods for determining the cold filter plugging point of products such as diesel and domestic heating oils using manual apparatus and automatic apparatus (Chapter 1).
• Applicable to fatty acid methyl esters (FAME), distillate fuels and synthetic diesel fuels, including fuels containing fatty acid methyl esters (FAME), flow improvers or other additives, for use in diesel engines and domestic heating installations (Chapter 1).
• Precision applicable range: cold filter plugging point range is −47 ℃~11 ℃; outside this range the precision of this standard is not applicable (14.1).
• Not applicable: no explicit non-applicable clauses are listed in the source text.

3. Method principle

The sample is cooled under specified conditions and, through a 2 kPa controllable vacuum device, is drawn through a standard wire mesh filter into a pipette. Each time the sample is 1 ℃ below the previous temperature, this step is repeated until the amount of waxy crystals precipitated in the sample is sufficient to stop flow or reduce the flow rate; the temperature at which the time for the sample to fill the pipette exceeds 60 s or the sample cannot completely return to the test cup is recorded as the cold filter plugging point of the sample (Chapter 4).

4. Reagents and materials (purity / preparation)

• 7.1 n-Heptane: analytical reagent.
• 7.2 Acetone: analytical reagent.
• 7.3 Quantitative filter paper.
• 7.4 Calibration standards: such as certified reference materials, working standards, etc.
• Preparation method: not provided in the available source.

5. Apparatus and equipment

5.1 Manual apparatus (6.1)

• 6.1.1 General: the apparatus is assembled according to Figure 1, see 6.1.2~6.1.14 for details. Warning: instrument parts are made of copper, zinc and brass; fatty acid methyl esters (FAME) can affect metal parts, so parts should be protected or made from alternative materials.
• 6.1.2 Test cup: made of transparent glass, flat-bottomed cylindrical, inner diameter 31.5 mm±0.5 mm, wall thickness 1.25 mm±0.25 mm, height 120 mm±5 mm, with a horizontal mark at 45 mL of the test cup.
• 6.1.3 Jacket: made of brass, flat-bottomed cylindrical, waterproof, can be used as an air bath. Inner diameter 45 mm±0.25 mm, outer diameter 48 mm±0.25 mm, height 115 mm±3 mm (see Figure 2).
• 6.1.4 Insulating ring: made of oil-resistant plastic or other suitable material, placed at the bottom of the jacket to provide thermal insulation. The outer diameter of the insulating ring should match the inner diameter of the jacket, and the thickness is 6 +0.3/0 mm (see Figure 3).
• 6.1.5 Positioning rings (two): made of oil-resistant plastic or other suitable material, about 5 mm thick, placed as shown in Figure 1, surrounding the test cup. The positioning rings should fit tightly around the test cup and yet fit exactly into the jacket. To facilitate fitting over the test cup, the positioning rings are not closed and should have a 2 mm annular gap to accommodate variations in test cup diameter. The positioning rings and insulating ring may be made as a single unit, see Figure 3.
• 6.1.6 Support ring: made of oil-resistant plastic or other suitable non-adsorptive, oil-resistant non-metallic material, placed in a suitable position in the cooling bath to suspend the jacket vertically and stably, with the stopper centered, see Figure 4 for details. Other support rings meeting the cooling bath requirements may also be used.
• 6.1.7 Stopper: made of oil-resistant plastic or other suitable non-adsorptive, oil-resistant non-metallic material; assembly with the test cup and support ring is shown in Figure 5. The stopper has three holes, two of which respectively receive the pipette and thermometer, and the other is used to maintain pressure balance in the system. When using a high-range thermometer (glass thermometer), a groove may be made in the upper part of the stopper if necessary to facilitate reading the temperature at −30 ℃. A metal spring clip is fitted into the stopper hole where the thermometer is inserted to secure the thermometer.
• 6.1.8 Pipette and filter assembly:
  • 6.1.8.1 Pipette: made of transparent glass, with a marked line at 149 mm±0.5 mm from the bottom of the pipette (see Figure 6) (capable of containing a sample volume of 20 mL±0.2 mL). The pipette should be connected to the filter.
  • 6.1.8.2 Filter (see Figure 7): threads should meet the requirements of GB/T 193, including the following components:
    • a) Brass housing: threaded housing with filter mesh. The housing should be fixed to an O-shaped ring made of oil-resistant plastic. The inner diameter of the central tube is 4 mm±0.1 mm.
    • b) Brass nut: the upper part connects to the pipette, the lower part connects to the filter mesh; the connection must be leak-free, see Figure 7 for details.
    • c) Filter mesh: diameter 15 mm, plain weave stainless steel wire mesh, mesh opening size 45 μm, wire diameter 32 μm; mesh opening tolerances should meet the following requirements: mesh openings exceeding the basic size by no more than 22 μm; the deviation range of the average mesh opening size from the basic size must not exceed ±3.1 μm; the number of mesh openings exceeding the basic size by 13 μm must not exceed 6% of the total number of mesh openings. Note: for requirements for wire woven mesh, refer to GB/T 6003.1.
    • d) Brass filter base: the filter mesh is pressed into the housing of the filter base with a retaining ring; the diameter of the exposed portion of the wire woven mesh is 12 +0.1/0 mm (see Figure 8).
    • e) Brass can: with external threads; this brass leg and the O-shaped ring can be screwed into the brass filter base; the bottom end has 4 orifices to allow sample to enter the filter.
• 6.1.9 Glass liquid thermometer:
  • 6.1.9.1 High-range thermometer (GB/T 514—2005 in GB-37): temperature range −38 ℃~50 ℃, used for determining samples with cold filter plugging point higher than −30 ℃ (including −30 ℃).
  • 6.1.9.2 Low-range thermometer (GB/T 514—2005 in GB-36): temperature range −80 ℃~20 ℃, used for determining samples with cold filter plugging point lower than −30 ℃.
  • 6.1.9.3 Thermometer for cooling bath: temperature range −80 ℃~20 ℃.
• 6.1.10 Cooling bath:
  • 6.1.10.1 Any type of cooling bath may be used, but it should have suitable shape and dimensions to ensure the jacket can be fixed vertically in the required position.
  • 6.1.10.2 The cooling bath should be equipped with a lid with single or multiple holes to place the support ring; the jacket may be permanently fixed to the lid.
  • 6.1.10.3 Through a refrigeration device or suitable cooling medium, the bath temperature is maintained within the specified temperature range; the cooling medium is stirred or otherwise agitated to ensure uniform temperature in the cooling bath. Table 1 lists the cooling bath temperatures used for different cold filter plugging points. These temperatures can be obtained by multiple cooling baths or by adjusting the refrigeration device. If only a refrigeration device is used, the bath temperature should be capable of dropping to the next temperature point within 2.5 min. If multiple jackets are placed in one large cooling bath at the same time, the spacing between jacket walls should be at least 50 mm.
  • Table 1 Cooling bath temperature:

• 6.1.11 Three-way valve: made of glass, with a bidirectional inclined bore of diameter 3 mm.
• 6.1.12 Vacuum source: a vacuum pump or water pump with sufficient pressure to ensure that the air flow rate in the vacuum regulating device during the entire suction process of the test is 15 L/h±1 L/h.
• 6.1.13 Vacuum regulating device: composed of a glass bottle, at least 350 mm in height, capable of being filled with at least 5 L of water and sealed with a stopper; the stopper has three holes and is fitted with glass tubes of suitable diameter. Two of these are short tubes whose insertion depth should be above the water surface. The third tube has an inner diameter of 10 mm±1 mm; when one end is a few centimeters above the stopper, the other end should be able to be inserted to about 200 mm below the water surface. The insertion depth should be adjusted so that the pressure difference of the water level manometer is 2 kPa±0.05 kPa (200 mmH₂O±1 mmH₂O). Another 5 L empty bottle should be connected horizontally to the vacuum regulating device to provide a constant pressure for the vacuum source; the arrangement is shown schematically in Figure 1.
• 6.1.14 Stopwatch: accuracy of 0.2 s or higher, with an accuracy of 0.10% within 10 min.

5.2 Automatic apparatus (6.2)

• 6.2.1 The automatic apparatus shall include devices meeting the requirements of 6.1.2~6.1.8 and 6.1.12, a refrigeration device, a digital thermometer, an automatic detection system, an electronic vacuum regulator, and a time measuring device.
• 6.2.2 Refrigeration device: ensure that the cooling temperature can reach the requirements specified in Table 1, and it shall be able to drop to the next temperature point within 2.5 min.
• 6.2.3 Digital thermometer: two digital-display platinum resistance thermometers are used respectively to measure the temperature of the sample and the cooling temperature of the refrigeration device, with a resolution of 0.1 ℃ and an accuracy of 0.5 ℃. For technical conditions, see Appendix A.
• 6.2.4 Automatic detection system: includes one sensor to record the filling condition of the pipette, suction 20 mL±0.2 mL, 20 mL is marked, and another sensor to position 85 mm±4 mm, recording the position of the bottom of the pipette.
• 6.2.5 Electronic vacuum regulator: capable of maintaining 2 kPa±0.05 kPa throughout the entire test process.
• 6.2.6 Time measuring device: accuracy of 0.2 s or higher, with an accuracy of 0.10% within 10 min.

5.3 Appendix A Technical conditions for thermometers (normative appendix)

This appendix gives the dimensional specifications of the digital thermometer (6.2.2). Table A.1 gives the dimensions of each part of the platinum resistance thermometer (PRT), see Figure A.1. For platinum resistance thermometers manufactured with an all-metal stem, the supplier shall confirm that the thermometer dimensions meet the requirements of Table A.1.

Table A.1 Thermometer dimensions:

6. Recommended operating conditions

• Cold bath temperature: according to Table 1, when the expected cold filter plugging point is higher than −20 ℃, the cold bath temperature is −34 ℃±0.5 ℃; at −20 ℃~−35 ℃, −34 ℃±0.5 ℃, then −51 ℃±1.0 ℃; below −35 ℃, −34 ℃±0.5 ℃, then −51 ℃±1.0 ℃, and finally −67 ℃±2 ℃ (6.1.10.3).
• Vacuum pressure difference: 2 kPa±0.05 kPa (200 mmH₂O±1 mmH₂O) (6.1.13, 12.1.6).
• Air flow rate: 15 L/h±1 L/h (6.1.12, 12.1.6).
• Temperature of the test sample before being placed in the cold bath: 30 ℃±5 ℃ (Chapter 9, 12.1.5, 12.2.3).
• Distance from the bottom of the thermometer to the bottom of the test cup: 1.5 mm±0.2 mm (12.1.4, 12.2.3).
• Depth to which the sleeve is vertically placed in the cold bath (if it cannot be fully placed): 85 mm±2 mm (12.1.5).
• Cooling rate requirement: when only the refrigeration device is used, the bath temperature shall be able to ensure a drop to the next temperature point within 2.5 min (6.1.10.3, 6.2.2).

7. Sampling and test sample preparation

• Chapter 8 Sampling: unless otherwise specified, sampling shall be carried out in accordance with GB/T 4756 or GB/T 27867.
• Chapter 9 Preparation of test sample: at room temperature (temperature shall not be lower than 15 ℃), filter about 50 mL of the test sample on dry filter paper. Before testing, bring the test sample to 30 ℃±5 ℃.

8. Analytical procedure

8.1 Preparation of apparatus (Chapter 10)

• 10.1 The apparatus shall be adjusted according to the manufacturer's instructions. Before each test, disassemble the filter, clean all parts of the filter, the test cup, the pipette, and the thermometer with n-heptane, then rinse with acetone, and finally blow dry with filtered dry air. Check whether all accessories including the sleeve are completely clean and dry, and check whether the wire mesh and joints are damaged. If necessary, replace with new ones. Check whether the brass nut is tightened to prevent leakage.
• 10.2 The filter base shall be inspected periodically and cleaned as needed according to the sample type.

8.2 Calibration (Chapter 11)

• 11.1.1 The apparatus shall be calibrated at least twice a year, and if possible, certified reference materials shall be used. The apparatus shall be checked periodically with working standards of known cold filter plugging point. When the deviation of test results is greater than the standard repeatability, or abnormal quality control deviations occur, further analytical investigation of the test shall be carried out. The instrument manufacturer's manual shall provide guidance to ensure correct use and calibration of the apparatus.
• 11.1.2 The following instruments or equipment shall be calibrated periodically; unless otherwise specified, calibration once every six months is recommended.
• 11.2 Thermometer: shall be calibrated periodically, at least once a year. The thermometer shall be traceable to national standards.
• 11.3 Cold bath or refrigeration device: shall be checked with a calibrated thermometer.
• 11.4 Vacuum unit: shall be calibrated by means of a pressure gauge traceable to national standards or International System of Units standards.
• 11.5 Stopwatch or time measuring device: shall be calibrated periodically, at least once a year.

8.3 Manual apparatus test procedure (12.1)

• 12.1.1 Place the insulating ring at the bottom of the sleeve. Before placing the insulating ring into the sleeve, check that the sleeve does not contain water or ice.
• 12.1.2 If the positioning ring is not fixed on the insulating ring, the positioning ring shall be placed at 15 mm~75 mm from the bottom of the test cup.
• 12.1.3 Pour the filtered test sample into a clean, dry test cup up to the marked line.
• 12.1.4 Insert the stopper equipped with the thermometer and pipette (already pre-connected to the filter) into the test cup containing 45 mL of test sample, so that the thermometer is vertical, the bottom of the thermometer shall be 1.5 mm±0.2 mm from the bottom of the test cup, and the filter shall also be placed vertically at the bottom of the test cup. If the expected cold filter plugging point is lower than −30 ℃, when using a glass thermometer, a low-range thermometer shall be used, and the thermometer shall not be replaced during the test. Handle carefully to ensure that the thermometer does not contact the wall of the test cup or the filter.
• 12.1.5 When the test sample temperature reaches 30 ℃±5 ℃, open the stopper at the sleeve opening, and place the prepared test cup vertically into the sleeve that has been placed in a cold bath cooled to −34 ℃±0.5 ℃. If the sleeve cannot be fully placed in the cold bath, the sleeve shall be placed vertically in the cold bath at 85 mm±2 mm.
• 12.1.6 Connect the vacuum system to the three-way valve on the pipette with a flexible tube (see Figure 1). Before carrying out the measurement, do not connect the pipette to the vacuum source. Turn on the vacuum source, adjust the air flow rate to 15 L/h, and the U-shaped tube water level pressure difference gauge shall stably indicate a pressure difference of 2 kPa±0.05 kPa (200 mmH₂O±1 mmH₂O).
• 12.1.7 After the test cup is placed in the sleeve, when the test temperature reaches an integer value, the test may be started; however, if the cloud point of the sample is known, it is preferable to cool the sample directly to 5 ℃ above the cloud point, and when the sample temperature reaches a suitable integer degree, turn the three-way valve to start the test. The sample is drawn through the filter into the pipette, and timing starts at the same time. When the sample reaches the scale mark of the pipette, stop timing and turn the three-way valve to the initial position, so that the pipette is open to the atmosphere and the sample flows back naturally into the test cup.
• 12.1.8 If the time for the first filtration to reach the pipette scale mark exceeds 60 s, abandon this test and repeat the previous test at a slightly higher temperature.
• 12.1.9 Each time the sample temperature decreases by 1 ℃, repeat the operation until within 60 s the pipette can no longer draw 20 mL of sample. Record the temperature at the start of the last filtration as the cold filter plugging point of the sample. A few samples may exhibit irregular suction phenomena, that is, the suction time recorded in the test (the time for 20 mL of sample to be drawn into the pipette) is unexpectedly shortened, while continuing the test will show the suction time continuing to increase until reaching the 60 s limit.
• 12.1.10 When the sample drops to −20 ℃, if its cold filter plugging point has not yet been reached, the test cup shall be quickly transferred to a cold bath at −51 ℃±1 ℃ to continue the test, or the refrigeration device shall be adjusted to −51 ℃±1 ℃. Each time the sample temperature decreases by 1 ℃, repeat the operation of 12.1.7.
• 12.1.11 When the sample drops to −35 ℃, if its cold filter plugging point has not yet been reached, the test cup shall be quickly transferred to a cold bath at −67 ℃±2 ℃ to continue the test, or the refrigeration device shall be adjusted to −67 ℃±2 ℃. Each time the sample temperature decreases by 1 ℃, repeat the operation of 12.1.7. When the sample drops to −51 ℃, if the cold filter plugging point of the sample has not yet been reached, the test shall be stopped and the result reported as "not plugged at −51 ℃".
• 12.1.12 After cooling in accordance with 12.1.9, 12.1.10 and 12.1.11, if the time for 20 mL of sample to fill the pipette scale mark is less than 60 s, but when the three-way valve is turned to the initial position, the sample in the pipette cannot all flow back naturally into the test cup, record the temperature at the start of this filtration as the cold filter plugging point of the sample.

8.4 Automatic apparatus test procedure (12.2)

• 12.2.1 Place the insulating ring at the bottom of the sleeve. Before placing the insulating ring into the sleeve, check that the sleeve does not contain water or ice.
• 12.2.2 Pour the filtered test sample into a clean, dry test cup up to the mark (45 mL).
• 12.2.3 When the temperature of the test sample in the test cup reaches 30 ℃±5 ℃, place the test cup into the sleeve, insert the stopper fitted with the pipette (already connected to the filter) and thermometer vertically into the test cup, ensure that the filter is at the bottom of the test cup, check that the thermometer does not contact the wall of the test cup or the filter, and adjust the distance between the bottom of the thermometer and the bottom of the test cup to 1.5 mm±0.2 mm.
• 12.2.4 Connect the pipette to the vacuum system.
• 12.2.5 Start the test according to the requirements of the instrument manual and report the cold filter plugging point.

9. Qualitative and Quantitative and Calculation Formulas

• Chapter 13 Expression of Results: Report the recorded temperature as the cold filter plugging point of the test sample (see 12.1.9, 12.1.12 and 12.2.5), and report the result to the nearest integer.
• Definition of cold filter plugging point (3.1): The highest temperature at which, when the test sample is cooled under specified conditions, the test sample cannot pass through the filter, or the time for 20 mL of the test sample to pass through the filter is greater than 60 s, or the test sample cannot flow completely back into the test cup.
• Calculation formula: not provided in the available source (this standard is a temperature determination and has no calculation formula).

10. Precision

• 14.1 General: Precision tests were conducted in 2011. The samples used for precision verification included fatty acid methyl esters (FAME), domestic heating oil, and diesel fuels and synthetic diesel fuels containing a volume fraction of 0~30% fatty acid methyl esters. The cold filter plugging point range is −47 ℃~11 ℃; outside this range, the precision of this standard does not apply. Judge the reliability of test results according to the following provisions (95% confidence level).
• 14.2 Repeatability r: For repeated determinations by the same operator using the same instrument under the same operating conditions on the same test sample, the difference between two consecutive test results shall not exceed the requirement of formula (1):
  • r = 1.2 − 0.027 X₁ ……………………(1)
  • Where: X₁ — the average of the two results used for comparison.
• 14.3 Reproducibility R: For determinations by different operators in different laboratories on the same test sample, the difference between two single, independent test results shall not exceed the requirement of formula (2):
  • R = 3.0 − 0.060 X₂ ……………………(2)
  • Where: X₂ — the average of the two single, independent test results used for comparison.

11. Report

Chapter 15 The test report shall contain at least the following information:

• 15.1 Product type and number of the test sample
• 15.2 Reference to this standard
• 15.3 Sampling procedure (see Chapter 8)
• 15.4 Test results (see Chapter 13)
• 15.5 Any differences from the test procedure
• 15.6 Test date

12. Normative References

• GB/T 193 General purpose metric screw threads — Diameters and pitches series
• GB/T 514—2005 Technical specifications for liquid-in-glass thermometers for petroleum product testing
• GB/T 4756 Manual sampling of petroleum liquids
• GB/T 6003.1 Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth
• GB/T 27867 Automatic sampling of petroleum liquids in pipelines
• GB/T Drafted according to the rules given in 1.1—2009 (Foreword)
• IP 309/16 Diesel and domestic heating oils — Determination of cold filter plugging point — Stepwise cooling bath method (modified adoption)

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