SH/T 0100-1991 Determination of Solidification Point of Petroleum Wax

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Card type: Test method

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

• Method number: SH/T 0100-91
• Full name: Determination of Solidification Point of Petroleum Wax
• English name: not provided in the available source
• Replacement relationship: not provided in the available source (the source text marks "(confirmed in 1998)")
• Reference adoption: American Society for Testing and Materials standard ASTM D3944-80(85) "Determination of Solidification Point of Petroleum Wax" (see additional notes)

2. Scope of application and non-applicability

• Scope of application: This standard applies to paraffin wax and microcrystalline wax.
• Non-applicability: not provided in the available source.

3. Method principle

At room temperature, place the 50mg wax sample in a test tube and heat it above the solidification point of the sample. Then insert the thermocouple probe connected to the recorder into the sample. As the wax sample cools at room temperature, the thermocouple response curve of the cooling wax is immediately drawn on the recorder chart. The temperature at which the first significant change in the slope of the curve appears is the solidification point. (Chapter 4 Method summary)

Definition (Chapter 3): Solidification point of petroleum wax — the temperature at which the first significant change in the slope of the wax cooling curve appears when the sample changes from liquid to solid.

4. Reagents and materials (purity / preparation)

• Silicone rubber pad: fixes the thermocouple so that it is in the central position (see Figure 1) (5.4)
• Industrial filter paper (5.14)
• Ice water (used for recorder zero adjustment and cold-junction bath, see 6.3, A2)
• No other chemical reagents or purity and preparation requirements are provided in the available source.

5. Instruments and equipment

• 5.1 Thermocouple: iron—constantan or nickel-chromium—nickel-silicon. Sheathed two-core grounded-junction type, diameter 1.0mm, length 500.0mm, and formed by welding the two thermocouple wires together (diameter about 0.8mm).
• 5.2 Recorder: Hitachi 056 model or other models, but must meet the following requirements:
  • 5.2.1 Range: 0—5mV or 0—10mV
  • 5.2.2 Accuracy: full scale 0.25%
  • 5.2.3 Response time: full scale 1s
  • 5.2.4 Recorder paper speed is 10—20mm/min
• 5.3 Polyethylene clamp connector (see Figure 1)
• 5.4 Silicone rubber pad: fixes the thermocouple so that it is in the central position (see Figure 1)
• 5.5 Test tube: 6mm × 50mm
• 5.6 Vial: 25mm × 52mm
• 5.7 Apparatus for calibrating the temperature recorder:
  • 5.7.1 Stainless steel beaker or glass beaker: 1000mL
  • 5.7.2 Heating mantle: capacity 1000mL
  • 5.7.3 Variable-speed stirrer or homemade wire stirrer
  • 5.7.4 Thermometer: semi-immersion rod thermometer used in GB/T 8026
• 5.8 Apparatus for heating the wax sample:
  • 5.8.1 Hot air blower: 450W
  • 5.8.2 Heated aluminum block: about 50mm × 50mm × 50mm, with a hole drilled at the center of one face with a diameter of about 7mm and a depth of 37mm, to accommodate a 6mm × 50mm test tube, and an adjacent hole about 9mm × 38mm, able to accommodate a 45W external-heating electric soldering iron core (see Figure 2)
• 5.9 Autotransformer: controls the temperature of the heated aluminum block
• 5.10 Analytical balance: accurate to 0.001g
• 5.11 Thermos bottle
• 5.12 Glass tube: about 15mm × 150mm, used to place the cold junction of the thermocouple
• 5.13 Stand: fixes the thermocouple
• 5.14 Industrial filter paper

6. Recommended operating conditions

• Recorder paper speed: 10—20mm/min (5.2.4)
• Aluminum heating block heating voltage: paraffin wax 110—130V; microcrystalline wax 140—160V (6.4)
• Sample heating temperature: raise to above the expected solidification point 10—15℃ (6.5)
• Recorder standard curve calibration period: when used frequently, calibrate at least every 60d (6.1)

7. Sampling and sample preparation

• 6.2 Weigh 50mg±5mg of a representative sample and place it in a test tube.
• 6.5.1 For some microcrystalline waxes, when the slope of the drawn curve shows no obvious change, switch to a thermocouple formed by welding the two thermocouple wires together for testing, and increase the sample amount to 100—150mg.

8. Analytical procedure

• 6.1 Calibration of the recorder standard curve: when the recorder is used frequently, this curve should be calibrated at least every 60d (see Appendix A).
• 6.2 Weigh 50mg±5mg of a representative sample and place it in a test tube.
• 6.3 Connect the recorder input end to the thermocouple cold junction, place it in a glass tube and place it in a 0℃ (ice water) bath, and start the recorder.
• 6.4 Heat the test tube containing the sample with a blower or aluminum heating block (when using the aluminum heating block to heat paraffin wax and microcrystalline wax, adjust the autotransformer voltage to 110—130V and 140—160V respectively). During heating, care should be taken to heat the wax sample slowly and uniformly, avoiding local overheating; overheated wax deteriorates and can affect the test results.
• 6.5 After the sample melts, insert the thermocouple probe into the molten sample and raise the temperature to above the expected solidification point 10—15℃; at the same time, the recorder response curve is drawn accordingly, then turn off the blower and move the test tube containing the sample to a vial to cool. During this process, the curve on the recorder chart is continuously drawn until it becomes horizontal; turn off the recorder and confirm that the temperature corresponding to the point of the first significant change in slope on the curve is the solidification point of the sample.
  • 6.5.1 For some microcrystalline waxes, when the slope of the drawn curve shows no obvious change, switch to a thermocouple formed by welding the two thermocouple wires together for testing, and increase the sample amount to 100—150mg, so that the solidification point can be obtained.
• 6.6 After the test is completed, remelt the sample, wipe the test tube clean with industrial filter paper, and set it aside for use.

Appendix A Calibration of recorder standard curve (supplementary document):

• A1 The calibration apparatus consists of a 1000mL beaker and a thermometer and thermocouple probe immersed in the center of the beaker and at the same horizontal position.
• A2 Adjustment of recorder zero point: insert the thermocouple probe into a glass tube in a thermos bottle containing ice water so that it is at the same temperature as the thermocouple cold junction, start the recorder, and adjust its zero point.
• A3 Place about 95℃ of water in a beaker and stir it thoroughly with a variable-speed stirrer (or homemade wire stirrer). As the water cools, accurately record the thermometer reading and the recorder pen reading (in millivolts), taking a series of corresponding values at temperature intervals of 5℃, until the temperature of the water in the beaker drops to 50℃.
• A4 Draw the standard curve: use the recorder pen reading as the abscissa (X axis) and the thermometer reading as the ordinate (Y axis) to draw a standard curve; using this curve, the correct solidification point can be obtained.

9. Qualitative and quantitative determination and calculation formulas

• Solidification point determination: the temperature corresponding to the point of the first significant change in slope on the cooling curve is the solidification point of the sample (6.5, Figure 3).
• Result calculation: take the arithmetic mean of the two results of duplicate determination as the test result, read to 0.1℃ (Chapter 8 Report).
• Calculation formula: not provided in the available source.

10. Precision

Precision table (℃):

• 7.1 Repeatability: the difference between two results of duplicate determination shall not be greater than the value in the table below.
• 7.2 Reproducibility: the difference between two results determined by different laboratories shall not be greater than the value in the table below.

11. Report

Take the arithmetic mean of the two results of duplicate determination as the test result, read to 0.1℃. (Chapter 8)

12. Referenced documents

• GB/T 8026 Determination of Drop Melting Point of Petroleum Wax and Petrolatum (Chapter 2 Referenced standards; its semi-immersion rod thermometer see 5.7.4)
• ASTM D3944-80(85) "Determination of Solidification Point of Petroleum Wax" (reference adoption, see additional notes)

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 Q&A