SH/T 0638-1996 Determination of Oil Content in Microcrystalline Wax (Volumetric Method)

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Card type: Test method

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

• Standard number: SH/T 0638-1996
• Chinese name: Determination of Oil Content in Microcrystalline Wax (Volumetric Method)
• English name: not provided in the available source
• Adoption relationship: Non-equivalent adoption of international standard ISO 2908-1974 "Determination of Oil Content in Petroleum Wax", using the volumetric method to determine the oil content of microcrystalline wax. The conditions for wax-to-solvent ratio, cooling, condensation, stirring, and filtration are the same as in ISO 2908; only the sample amount is increased, the sample is dissolved using reflux condensation, and the filtrate is taken by the volumetric method.
• Replacement relationship: Effective from the date of publication, replacing SH 0013—0 in the technical requirements table of the "Microcrystalline Wax" product standard GB/T 3554 (original text as such, requires confirmation against the source standard (source-text extraction)).
• Technical committee: Technical committee of Fushun Research Institute of Petroleum and Petrochemicals.
• Drafting organization: Fushun Research Institute of Petroleum and Petrochemicals.
• Drafters: Yang Lingru, Li Yumin, Guo Hongjie.
• Approval/implementation: Approved by China Petrochemical Corporation 1996-12-20, implemented on 1997-07-01.

2. Scope of application and non-applicability

• Applicable to the determination of microcrystalline wax and mixed crystal wax with a freezing point above 30℃ and an oil content not greater than 15%(m/m), and also applicable to paraffin wax.
• Not applicable to certain waxes with an oil content greater than 5%(m/m) that cannot completely dissolve in methyl ethyl ketone and form layers.

3. Method principle

Take 4g wax sample, add 60mL methyl ethyl ketone, heat under reflux to dissolve the sample, cool the solution to −32℃ (original text is "one3290", requires confirmation against the source standard (source-text extraction)), and precipitate the wax. Filter and re-take 15mL filtrate. Evaporate the methyl ethyl ketone from the filtrate, weigh the residual oil, and calculate the oil content of the wax.

4. Reagents and materials (purity / preparation)

• Methyl ethyl ketone: analytical reagent. Evaporate 15mL methyl ethyl ketone, the residue shall not exceed 0.0004g (original text is ".00048", requires confirmation against the source standard (source-text extraction)), the test method is carried out according to 6.10.

5. Apparatus and equipment

5.1 Microcrystalline wax oil content tester: includes the following special instruments.

• 5.1.1 Oil-wax separator: includes a fritted glass filter (determine the pore size according to GB/T 3554 Appendix A and meet the requirements of that standard); sample tubes (two per set) and a condenser. The filter and condenser are connected to the sample tube by ground joints, see Figure 1.
• 5.1.2 Sample pipette: 5.4mL, marked at 5.2mL, with graduations of 0.2mL above and below the mark, minimum division 0.05mL.
• 5.1.3 Methyl ethyl ketone pipette: 15mL, 30mL. After calibration, accurate to 15mL±0.05mL and 30mL±0.10mL respectively (original text is "[unreadable value]mL" "30mL[unreadable sign]0.10ML", requires confirmation against the source standard (source-text extraction)).
• 5.1.4 Filtrate volume measuring tube: 14.5mL±0.1mL, graduation 0.1mL, with graduations of 0.5mL at top and bottom. Equipped with a polytetrafluoroethylene stopcock, see Figure 2.
• 5.1.5 Conical weighing bottle: 25～30mL. With a hollow ground stopper.
• 5.1.6 Thermometer: meets the requirements of GB/T 3554 "1.6" thermometer, used for low-temperature cooling bath.
• 5.1.7 Glass stirring rod: diameter 5mm, length about 300mm, slightly bent at the insertion end at 30～40mm, and ensure the upper and lower ends are parallel, so that the lower end easily contacts the bottle wall.
• 5.1.8 Wax melting oven: 70～100℃.
• 5.1.9 Wax melting bath: 0℃±5℃ (original text is "0 ℃[unreadable sign]5 9C", requires confirmation against the source standard (source-text extraction)).
• 5.1.10 Cold wax bath: 0℃～1℃ (original text is "0℃[unreadable separator]19c", requires confirmation against the source standard (source-text extraction)).
• 5.1.11 Low-temperature cooling bath: −34.5℃±1℃ with constant temperature, using ethanol as the medium.
• 5.1.12 Evaporation device: ensure that each nozzle blows clean air into the bottle at 2～3L/min, and the temperature around the bottle is maintained at 35℃±1℃. See Figure 3.
• 5.1.13 Air compression pump: provides a stable and sufficient clean air flow for the evaporation device; for this purpose, a purification tower is equipped. The total air flow can be measured with a float flowmeter, and the air volume of each nozzle can be measured with a soap film flowmeter.
• 5.1.14 Pressure reducing valve: provides an air flow with uniform flow rate and appropriate pressure for the oil-wax separator.

5.2 General instruments

• 5.2.1 Beaker: 100mL.
• 5.2.2 Balance: sensitivity 0.1mg (original text is "0. lm", requires confirmation against the source standard (source-text extraction)).

6. Recommended operating conditions

• Wax melting oven temperature: 70～100℃ (5.1.8).
• Wax melting bath temperature: 0℃±5℃ (5.1.9).
• Cold wax bath temperature: 0℃～1℃ (5.1.10, requires confirmation against the source standard (source-text extraction)).
• Low-temperature cooling bath temperature: −34.5℃±1℃, ethanol as medium (5.1.11).
• Evaporation device temperature: 35℃±1℃ (5.1.12).
• Evaporation air flow: each nozzle 2～3L/min (5.1.12).
• Filtration filtrate temperature range: 0℃～20℃ (6.9).
• Cooling endpoint temperature: −31.7℃±0.3℃ (6.7).

7. Sampling and sample preparation

• 6.1 Take a representative sample of about 50g and place it in a 100mL beaker, place it in a wax melting oven (5.1.8) controlled at a temperature above the wax freezing point (determined according to SH/T 0132) by 10～20℃, also place the sample tube (5.1.1) and sample pipette (5.1.2) in at the same time, after the wax sample melts and is mixed evenly, use the sample pipette to take about 5.2mL sample and add it to the sample tube.
• Note: Measure about 5.2mL molten wax, generally within the range of 4g±0.2g, each operator shall use the weighing method to calibrate the volume of the instruments used and different grades of wax samples.
• 6.2 Take out the sample tube, after slight cooling, rotate the sample tube so that the wax sample solidifies evenly on the tube wall, and its height does not exceed the height after adding solvent.

8. Analysis procedure

• 6.3 Add 60mL methyl ethyl ketone to the sample tube, connect the condenser (5.1.1), and place it in the wax melting bath (5.1.9), dissolve the sample under solvent reflux condensation conditions to avoid solvent loss.
• 6.4 After a transparent solution is formed (waxes with higher melting points are allowed to form a uniform misty mixture), remove from the wax melting bath, and after reflux stops, remove the condenser.
• 6.5 Place the sample tube in the cold wax bath (5.1.10) for 10min, so that the solution becomes a paste.
  • Note: At this time, the solvent loss can be determined by weighing; when multiple weighings are below 1%(m/m), the weighing step can be omitted.
• 6.6 Move the sample tube into a low-temperature cooling bath (5.1.11) at −34.5℃±1℃, and at the same time insert the fritted glass filter wrapped in filter paper into an empty sample tube previously placed in the low-temperature cooling bath.
• 6.7 First use a glass stirrer (5.1.7) to vigorously stir the paste to prevent the wax from agglomerating and adhering to the tube wall, causing oil entrapment in the wax. After the wax forms fine crystalline particles, insert the thermometer (5.1.6), and under gentle stirring with the thermometer, cool the paste to −31.7℃±0.3℃.
• 6.8 Take out the fritted glass filter that has been cooled in the low-temperature cooling bath for at least 10min, quickly wipe the tube wall with filter paper, place it into the sample tube from which the thermometer has been removed, the ground stopper must be sealed, and connect the glass hooks with a spring or rubber band.
  • Note: The fritted glass filter should not stay in the air for too long to avoid the formation of a frost layer on the wall.
• 6.9 Connect the compressed air to the fritted glass filter, slowly press the filtrate into the filtrate volume measuring tube (5.1.4), so that the filtrate height is more than half of the large bulb, and take 14.5mL filtrate within the range of 0℃～20℃.
• 6.10 Place the uncovered conical weighing bottle containing the filtrate in the evaporation device (5.1.12) kept at a constant temperature of 35℃±1℃, make the air nozzle concentric with the bottle neck, the nozzle tip is higher than the liquid surface by 15mm～5mm (original text is "15mm - 5mm", requires confirmation against the source standard (source-text extraction)), blow with an air flow of 2～3L/min for 30～50min, move into a desiccator without desiccant, cover the bottle cap, let stand near the balance for 10min, weigh to the nearest 0.0001g, repeat the operation, blowing for 5min each time, until the difference between two consecutive weighings does not exceed 0.0002g. Prevent high results due to excessive air humidity or dust in the air.

9. Qualitative and quantitative and calculation formula

The oil content of microcrystalline wax is expressed as mass percentage (X), calculated by formula (1):

X = 100m − 0.15 ……………………………………(1)

Where:

• m—— is equivalent to the mass of oil contained in 15mL sample, g (original text is "equivalent to the mass of oil contained in her sample", requires confirmation against the source standard (source-text extraction));
• 0.15—— is the average correction value for wax dissolved in the solvent at −31.7℃.

10. Precision

Precision (95% confidence level):

• 8.1 Repeatability: the difference between repeated determinations by the same operator shall not be greater than 0.06 plus 8% of the average value (original text is "0.06 plus 8% of the average value", requires confirmation against the source standard (source-text extraction)).
• 8.2 Reproducibility: the difference between test results submitted by two laboratories shall not be greater than 0.2 plus 11% of the average value (original text is "0.2 plus 11% of the average value", requires confirmation against the source standard (source-text extraction)).

11. Report

Take the average of parallel determinations as the oil content determination result; if it is a negative value, the oil content is zero.

12. Referenced documents

• GB/T 3554 Determination of Oil Content in Petroleum Wax
• SH/T 0132 Determination of Freezing Point of Petroleum Wax
• Note: Unless otherwise specified in the standard, the above referenced standards shall be the currently effective versions.

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