GB/T 30514-2014 Glass capillary kinematic viscometers — Specifications and operating instructions

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

• Standard number: GB/T 30514-2014
• Chinese title: Glass capillary kinematic viscometers — Specifications and operating instructions
• English title: Glass capillary kinematic viscometers—Specifications and operating instructions
• Adoption relationship: Modified adoption by redrafting method of ISO 3105:1994 (MOD)
• Replacement relationship: not provided in the available source (the foreword does not give the replaced standard number)
• Publication/implementation: published on 2014-02-19, implemented on 2014-06-01
• Drafting rules: drafted in accordance with GB/T 1.1—2009
• Compared with ISO 3105:1994, Chapter 8 and Chapter 9 are added structurally

2. Scope of application and non-application

• This standard specifies the specifications and operating instructions for glass capillary kinematic viscometers, and also specifies the calibration method for these viscometers.
• It applies to glass capillary viscometers used in the determination of kinematic viscosity of petroleum products according to the procedure of GB/T 30515.
• Specified viscometer types: improved Ostwald (Ostwald) (Ostwald) viscometer (Annex A), suspended-level viscometer (Annex B), reverse-flow viscometer (Annex C).
• Other glass capillary viscometers that can meet the precision requirements for kinematic viscosity determination of GB/T 30515 may also be used.
• Note: It has been verified that the BMN-1 type and BMN-2 type Pinkevich (Pinkevitch) viscometers in SH/T 0173-1992 can meet the precision requirements for the determination of kinematic viscosity of transparent liquid petroleum products in GB/T 30515; the BMN-3 type Cannon-Fenske (Cannon-Fenske) opaque viscometer in SH/T 0173-1992 can meet the precision requirements for the determination of kinematic viscosity of opaque liquid petroleum products in GB/T 30515.
• Non-application scope: no explicit "non-application" clause is provided in the available source.
• Warning: The use of this standard may involve certain hazardous materials, operations and equipment, but it does not purport to address all safety problems associated with this. It is the responsibility of the user of this standard to establish appropriate safety and protection measures and to determine the applicability of relevant regulatory limitations before applying this standard.

3. Method principle

• In principle, based on the Hagen-Poiseuille (Hagen-Poiseuille) law, the calculation of kinematic viscosity is related to the viscometer dimensions, see equation (4): v = [10⁶πrgd⁴ht/(128VL)] − E/t² Where: v— kinematic viscosity (mm²/s); g— gravitational acceleration (m/s²); d— capillary diameter (m); l— capillary length (m); h— average distance between the upper and lower menisci of the liquid (average driving head) (m); V— volume of liquid timed through the capillary (approximately the volume of the timing bulb) (m³); E— kinetic energy coefficient (mm²·s); t— flow time (s).
• If the minimum flow time of the selected viscometer exceeds the value specified in Annex A to Annex C, the kinetic energy correction term E/t² may be neglected, and equation (4) simplifies to equation (5): v = Ct
• Kinetic energy correction: designed according to Annex A to Annex C, when the flow time is greater than 200 s, the kinetic energy correction term E/t² may be neglected. For several sizes of viscometers required for measuring liquids of low kinematic viscosity, the minimum flow time is required to be greater than 200 s (specifically given in the footnotes of the corresponding size tables in Annex A to Annex C). For viscometers with constant C ≤ 0.01 mm²/s², if the minimum flow time does not reach 200 s, the kinetic energy correction term may be relatively large.
• Maximum flow time: 1000 s is artificially determined as the recommended maximum flow time; longer flow times may also be used.
• Surface tension correction: if within the flow time the average diameters of the upper and lower menisci of the liquid are not the same, and the surface tension of the test sample is substantially different from that of the calibration liquid, then surface tension correction is required; after correction, the constant Ccor is approximately obtained according to equation (6) (given by equation 6 in the source, containing parameters such as g, h, r₀, r₁, γ, ρ; the subscripts c and t denote the calibration liquid and the test sample, respectively).
• Temperature influence:
  • For viscometers in which the sample volume is adjusted at the bath temperature and for all suspended-level viscometers, the constant C is not affected by temperature.
  • For viscometers in which the sample liquid volume is fixed when filled at ambient temperature, the constant C changes with temperature: Cannon-Fenske routine viscometer, Pinkevich viscometer, Cannon-Manning semi-micro viscometer, Cannon-Fenske opaque viscometer.
  • Equation (7) is used to calculate the constants of Cannon-Fenske routine viscometers, Pinkevich viscometers, and Cannon-Manning semi-micro viscometers at other test temperatures different from the calibration temperature.
  • Equation (8) is used for calculating the temperature influence on the constant of the Cannon-Fenske opaque viscometer.

4. Reagents and materials (purity / preparation)

• Calibration oils: oils that are clear, free of solid particles and have Newtonian fluid characteristics; their kinematic viscosity should be within the kinematic viscosity measurement range of the standard viscometer and the viscometer being calibrated, and the minimum flow time in both should be greater than the value specified in the corresponding table of the annex, so that the kinetic energy correction (see 7.1 and 7.2) is less than 0.2%.
• Viscosity standard oils: Table 1 lists viscosity standard oils with the approximate kinematic viscosities shown; their recognized reference values of kinematic viscosity may be determined by interlaboratory collaborative tests and are provided together with the viscosity standard oils. Viscosity standard oils meeting the requirements of SH/T 0526 may also be used.
• Typical viscosity standard oil designations in Table 1: 3, 6, 20, 60, 200, 600, 2000, 8000, 30000 (for the corresponding approximate kinematic viscosity values see Table 1 in the source, including the temperature columns −40 ℃, 20 ℃, 25 ℃, 40 ℃, 50 ℃, 100 ℃; the value source-text extraction is doubtful and requires confirmation against the source standard (source-text extraction)).
• Cleaning solvents: first rinse several times with a suitable solvent that is completely miscible with the sample, then thoroughly clean with a completely volatile solvent; alkaline cleaning solutions are not recommended (they may cause changes in the viscometer calibration value).
• Drying air: filtered dry air stream.
• Filtration: if the sample is considered to contain fibers or solid particles, use a 75 μm screen for filtration when filling the sample.
• Distilled water: used as the initial reference liquid for kinematic viscosity (see Note 1 of 6.2.2).

5. Apparatus and equipment

• Glass capillary kinematic viscometers (improved Ostwald viscometer, suspended-level viscometer, reverse-flow viscometer; see Annexes A, B, C for details).
• Constant-temperature bath: the diameter of the opening in the bath cover is 51 mm (except for the FitzSimons viscometer and the Atlantek viscometer, all viscometers should be constructed to be suitable for placement through this opening); the depth of the liquid in the constant-temperature bath is at least 280 mm; set the distance from the liquid surface of the constant-temperature bath to the top of the bath cover to no more than 45 mm.
• Holder: ensures that tube L is vertical (see Chapter 5 for details).
• Plumb line or other equally accurate inspection means.
• Vacuum suction device / pressure device (used for filling and driving the sample).
• Rubber stoppers, short rubber tubing with screw clamp, three-way stopcock, etc. (depending on the viscometer type).
• Pipette (long pipette, used for loading samples into BS/U type or BS/U/M small viscometers).
• Stopwatch/timing device (flow time accurate to 0.1 s).
• Standard viscometer (driving head at least 400 mm, see Note 1 of 6.2.2).
• Constant-temperature bath cover: round metal cover (fits the opening 51 mm), 25 mm×59 mm rectangular metal cover (used for the Zeitfuchs cross-arm viscometer and the Zeitfuchs viscometer).

6. Recommended operating conditions

• Viscometer material: made of fully annealed, low-expansion borosilicate glass (4.1).
• Each viscometer should be permanently marked with the size designation, serial number and manufacturer's identification; all timing marks should be etched and filled with an opaque pigment, or made a permanent part of the viscometer (4.1).
• Dimensional tolerances: the dimensional tolerances of each tube length and bulb in the viscometer diagrams in Annex A to Annex C should be kept within ±10% or ±10 mm, whichever is smaller; the change in the viscometer calibration constant will not be greater than ±15% of the nominal value (4.2).
• Clamping and alignment (Chapter 5):
  • For all viscometers in which the centers of the upper and lower liquid levels are vertically aligned during the flow time (the Cannon-Fenske routine viscometer in Annex A and all viscometers in Annex B): tube L is within 1° of the vertical direction.
  • For viscometers in which the centers of the upper and lower liquid levels deviate during the flow time (viscometers other than the Cannon-Fenske routine viscometer in Annex A and all viscometers in Annex C): tube L is within 0.3° of the vertical direction.
• Temperature equilibration time: except for samples with very high kinematic viscosity, 30 min should be sufficient; the appropriate equilibration time needs to be determined by testing.
• Usually multiple viscometers may be placed in one bath; another viscometer should not be inserted or removed while one viscometer is being used for flow time determination.
• Flow time: should be greater than the minimum flow time specified in 200 s or in the corresponding viscometer size table, whichever is greater (A.2.1, B.2.1); the flow time of the reverse-flow viscometer should be greater than 200 s, and the kinetic energy correction should be less than 0.2% (C.2.1).
• Gravity acceleration correction: when the difference between the gravity acceleration g provided by the testing laboratory and the calibration laboratory is greater than 0.1%, the calibration constant is corrected according to formula (2): C₁ = (g₁/g₂)C₂; usually when the ratio of g₁ to g₂ is between 0.999 and 1.001, no gravity acceleration correction is required (6.2.5 note).
• Viscometer constant expression: report to the precision of 0.1% of its measured value; usually in the range 1×10⁻⁶ to 6.999×10⁻⁶ take four significant figures, in the range 7×10⁻⁶ to 9.99×10⁻⁶ take three significant figures (6.4).

7. Sampling and specimen preparation

• Fill the specimen into the viscometer according to the method required by the instrument design; this operation shall be consistent with the method used when calibrating the instrument (A.2.2, B.2.2, C.2.2).
• If the sample is considered to contain fibers or solid particles, use a 75 μm screen to filter when filling the specimen.
• For the specific filling methods of each type of viscometer, see Annex A.2.2, B.2.2, C.2.2 (including Cannon-Fenske routine viscometer, Cannon-Manning semi-micro viscometer, Pinkevitch viscometer, Zeitfuchs viscometer, SIL viscometer, BS/U type, BS/U/M small size, Ubbelohde, Cannon-Ubbelohde, BS/IP/SL, BS/IP/SL(S), BS/IP/MSL, FitzSimons, Atlantic, Cannon-Fenske opaque, Zeitfuchs cross-arm, Lantz-Zeitfuchs, BS/IP/RF U type, etc.).
• Requirements such as specimen amount, filling mark line, and constant volume at filling temperature/test temperature are detailed in each annex.

8. Analytical procedure

• Calibration method (Chapter 6):
  • 6.1 Test procedure: perform calibration according to the procedures described in Annex A to Annex C.
  • 6.2 Standard viscometer method:
    • 6.2.1 Select an oil (clear, free of solid particles, Newtonian fluid, kinematic viscosity within the measurement range of the standard viscometer and the viscometer being calibrated, minimum flow time greater than the value specified in the corresponding table of the annex, kinetic energy correction less than 0.2%).
    • 6.2.2 Select a calibrated viscometer with a known viscometer constant C₂; place the calibrated viscometer and the viscometer being calibrated in the same bath, and determine the oil flow time according to the method of GB/T 30515.
    • 6.2.3 The constant C₁ of the viscometer being calibrated is calculated according to formula (1): C₁ = (t₂×C₂)/t₁ (t₁, t₂ accurate to 0.1 s).
    • 6.2.4 Repeat 6.2.1 to 6.2.3 with a second oil whose flow time is at least 50% longer than that of the first oil; for the viscometers in Annex A and Annex B, if the difference between the two C₁ values is less than 0.2%, or for the viscometer in Annex C, if the difference between the two C₁ values is less than 0.3%, take the average as the constant of the viscometer being calibrated; if greater than the specified value, carefully check all possible causes of error and repeat the test.
    • 6.2.5 The calibration constant C depends on the gravity acceleration at the location of calibration; when the difference between the testing laboratory and the calibration laboratory g is greater than 0.1%, correct according to formula (2).
  • 6.3 Viscosity standard oil method:
    • 6.3.1 From Table 1, select a viscosity standard oil whose kinematic viscosity at the calibration temperature is within the kinematic viscosity range of the viscometer being calibrated, and whose minimum flow time is greater than the minimum flow time specified in the corresponding viscometer specification table of the annex; determine the flow time according to GB/T 30515, accurate to 0.1 s, and calculate the constant C according to formula (3): C = v/t.
    • 6.3.2 Re-determine with a second viscosity standard oil whose flow time is at least 50% longer than that of the first viscosity standard oil; the judgment rule is the same as 6.2.4.
  • 6.4 Expression of viscometer constant (see Section 6).
• Kinematic viscosity calculation (Chapter 7): see the method principle in Section 3.
• Viscometer calibration requirements (Chapter 8):
  • 8.1 Before sale or use, glass capillary kinematic viscometers shall be calibrated or verified in accordance with the relevant provisions of this standard; the calibration or verification results shall meet the technical specification requirements for the corresponding viscometer in this standard.
  • 8.2 For some working capillary viscometers, calibration and verification may be carried out in accordance with the national metrological verification regulation JJG 155.
• Operating instructions (Annex A.2, B.2, C.2): include steps such as selecting the viscometer, filling the specimen, constant temperature, suction/pressurization, timing, repeated determination, cleaning and drying; see each annex for details.

9. Qualitative and quantitative and calculation formulas

• Formula (1): C₁ = (t₂×C₂)/t₁
  • C₁—constant of the viscometer being calibrated (mm²/s²); t₁—flow time of the oil in the viscometer being calibrated (accurate to 0.1 s) (s); C₂—constant of the calibrated viscometer (mm²/s²); t₂—flow time of the oil in the calibrated viscometer (accurate to 0.1 s) (s).
• Formula (2): C₁ = (g₁/g₂)C₂ (subscripts 1 and 2 denote the testing laboratory and the calibration laboratory, respectively).
• Formula (3): C = v/t (v— kinematic viscosity of the viscosity standard oil, mm²/s; t— flow time, s).
• Formula (4): v = [10⁶πrgd⁴ht/(128VL)] − E/t² (for parameter meanings see Section 3).
• Formula (5): v = Ct
• Formula (6): Ccor = C{1 + [2/(gh)] × (1/r₀ − 1/r₁) × (γₜ/ρₜ − γc/ρc)} (for parameter meanings see the original text 7.4; subscripts c and t denote the calibration liquid and the specimen, respectively).
• Formula (7): Ca = C₃{1 + [4000V₁(p₂ − p₁)]/(πD₁h₁p₂)} (used for Cannon-Fenske routine viscometer, Pinkevitch viscometer, Cannon-Manning semi-micro viscometer; for parameter meanings see the original text 7.5.2.1).
• Formula (8): Ca = C₃{1 − [4000V₁(p₂ − p₁)]/(πD₂h₁p₂)} (used for Cannon-Fenske opaque viscometer; D₂ is the average diameter of the liquid meniscus in the upper reservoir of this viscometer, mm).
• Note: In formula (4) of the original text, source-text extraction contains symbols such as "10⁶πrgd⁴ht", among which "r" is suspected to be source-text extraction noise and requires confirmation against the source standard (source-text extraction).

10. Precision

• Judgment of consistency of calibration constants (6.2.4, 6.3.2):
  • Viscometers in Annex A and Annex B: if the difference between the two C values is less than 0.2%, take the average; if greater than the specified value, repeat the test.
  • Viscometer in Annex C: if the difference between the two C values is less than 0.3%, take the average; if greater than the specified value, repeat the test.
• Judgment of repeatability of flow time (A.2.6, B.2.6, C.2.6): the results of two determinations shall meet the determinacy tolerance requirements specified for the petroleum product being tested in the method of GB/T 30515, and the average shall be used to calculate/report the kinematic viscosity.
• The measurement precision of the viscometer in Annex C is slightly poorer than that of the viscometers in Annex A and Annex B (C.2.6).
• Note: This standard does not separately provide a precision numerical table for this standard; the precision refers to GB/T 30515.

11. Report

• Report the viscometer constant to the precision of 0.1% of its measured value; usually in the range 1×10⁻⁶ to 6.999×10⁻⁶ take four significant figures, in the range 7×10⁻⁶ to 9.99×10⁻⁶ take three significant figures (6.4).
• Reverse-flow viscometer: if the results of two determinations meet the determinacy tolerance requirements specified for the petroleum product being tested in the method of GB/T 30515, report the average of the two kinematic viscosity determination results (C.2.6).
• Other reporting requirements: not provided in the available source.

12. Referenced documents

• GB/T 27025 General requirements for the competence of testing and calibration laboratories (GB/T 27025—2008, ISO/IEC 17025:2005, IDT)
• GB/T 30515 Standard test method for kinematic viscosity of transparent and opaque liquid petroleum products and calculation of dynamic viscosity (GB/T 30515—2014, ISO 3104:1994, MOD)
• JJG 155 Verification regulation for working capillary viscometers
• SH/T 0173—1992 Technical specifications for glass capillary viscometers
• SH/T 0526 Viscosity standard oils
• Note: The foreword mentions that in the normative references of Chapter 2, JJG 155, SH/T 0173-1992 and SH/T 0526 were added.

13. Source and verification

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14. Quick reference for questions and answers