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Determination of flash point— Rapid equilibrium closed cup method


1 Scope

This standard specifies a kind of paint (water-based paint), varnish, lacquer base and adhesive with a closed cup flash point in the range of 130℃~300℃ Method for the determination of closed cup flash point of solvents, solvents, petroleum and related products. When using an instrument with a flash point detector (A.1.6), this standard also It is suitable for the determination of the flash point of fatty acid methyl esters (FAME).

2 Normative references

The clauses in the following documents become clauses of this standard through reference in this standard. For dated references, all subsequent The amendments (excluding errata content) or revisions do not apply to this standard, however, the parties to the agreement based on this standard are encouraged to study Is the latest version of these files available. For undated references, the latest edition applies to this standard.

GB/T 3186 Paint, Varnish and Raw Material Sampling for Paint and Varnish (GB/T 3186 2006, ISO 15528:2000,IDT)

GB/T 20777 Inspection and preparation of paint and varnish samples (GB/T 20777 2006, ISO 1513:1992, IDT)

SY/T 5317 Automatic sampling method of petroleum liquid pipeline (SY/T 5317–2006, ISO 3171:1988, IDT)

ISO 3170 Manual sampling of petroleum and liquid petroleum products

3 Terms and Definitions

The following terms and definitions apply to this standard.


flash point

Under the specified test conditions, when tested by the specified method, the vapor of the test sample can be instantly ignited by the test flame, and the flame Spread over the entire liquid surface and be corrected to the lowest temperature of the test sample at 101.3 kPa atmospheric pressure.

4 Principles

Inject a specified volume of test sample into a test cup maintained at the expected flash point temperature of the material to be tested, and after a specified period of time, ignite. And observe whether there is flashover, and continue the test with new samples at different temperature points until the flashpoint is measured and the specified sensitivity is reached.

5 Reagents and Materials

5.1 Cleaning solvent

A suitable solvent for removing residual specimens from the test cups and lids from previous tests.
NOTE: The choice of solvent will depend on the viscosity of the previous test material and residue. Low volatility aromatic (benzene-free) solvents can be used to remove petroleum residues, such as Mixed solvents such as benzene-acetone-methanol are effective for removing rubber-like deposits.

5.2 Calibration liquid

A series of certified reference materials (CRM) and/or secondary working standards (SWS)

6 instruments

6.1 General

The apparatus is shown in Appendix A. Appendix A contains the test cup and lid assembly, along with a detailed drawing of dimensions and special requirements, see Figure A. 1 to Figure A. 5. Testing for flash points over a range of 30°C to 300°C may require more than one instrument.

6.2 Syringe

6.2.1 2 mL syringe: Adjustable to add sample 2. oo mL ± 0.05 mL, if necessary, can be equipped with a needle, suitable for testing Use when the test temperature is not greater than 100°C. When testing FAME, 2 mL samples are used at all temperature points.

6.2.2 5mL syringe: can be adjusted to be able to add sample 4.00mL ± 0.10mL, if necessary, can be equipped with a needle, suitable for testing It is used when the test temperature is higher than 100°C. When testing FAME, a 5 mL syringe is not required.

6.3 Barometer: Accurate to 0.1 kPa, it is not necessary to use barometers used by meteorological stations and air stations, which are pre-calibrated to sea level readings.

6.4 Heater or oven (optional); if necessary, it can be used to heat the sample, and the temperature can be controlled within the range of ±5°C. If using the oven box, which should be truly safe for hydrocarbon vapors.

It is recommended that the oven be equipped with an explosion-proof device.

6.5 Cooler or refrigerator (optional): If necessary, can be used to cool the sample, can cool the sample to 10 ℃ below the expected flash point, and can The temperature is controlled within the range of ±5°C, and if a refrigerator is used, it should be equipped with an explosion-proof device.

6.6 Draft shield (optional): If it is necessary to minimize airflow, a draft shield can be installed on the back and sides of the instrument.
Note: A draft shield with a height of 350mm, a width of 480mm and a depth of 240mm is suitable.

6.7 Embedded cup (optional)
Note: For difficult-to-remove samples, a thin metal insert cup can be used.

7 Instrument Preparation

7.1 General

Choose the appropriate instrument based on the expected flash point temperature. Follow the instrument manufacturer’s instructions to properly set up and operate the instrument. for possibly Adhered material, insert cups may be used as described in Appendix D.

7.2 Installation of the instrument

Secure the instrument (Appendix A) to a stable, level surface in a windless position.
A draft shield is recommended when wind protection is ineffective.
Note: When testing materials that may generate toxic fumes, the instrument can be placed in a fume hood with a dedicated airflow controller. Adjust the airflow control so that the test Toxic gases can be extracted during the test without creating a draft around the test cup.

7.3 Cleaning of test cups and accessories

Clean the test cup, lid and accessories with a suitable solvent (5.1) to remove traces of resin or residue left by the previous test. according to Maintain the instrument according to the instrument manufacturer’s instructions.
Note 1: The last traces of the solvent used can be removed by blowing dry, clean air.
Note 2: The feeder nozzle can be easily cleaned with a pipe cleaner.

7.4 Instrument calibration

7.4.1 The standard function of the instrument shall be verified at least once a year by testing certified reference materials (CRM) (5.2). The difference between the result obtained and the given value of CRM shall be no more than 

, where R is the reproducibility limit of the method (see 13.3).

It is recommended that more frequent verification checks be done with the Secondary Working Standard (SWS,) (5.2).
Note: Appendix c gives the recommended procedures for calibrating instruments with CRM, and SWS and how to make SWS.

7.4.2 The values ​​obtained during the calibration check shall neither be used to provide a deviation report nor be used to provide information on the flash point of subsequent instrumental testing.line correction.

If the instrument calibration fails, it is recommended that the operator do the following checks:
a) Whether the lid and the test cup form an airtight seal;
b) Whether the shutter forms a light-tight seal;
c) Whether the mercury ball of the thermometer and the insert part of the cylinder are wrapped with enough thermal conductive glue to meet the requirements.

8 Sampling

8.1 Unless otherwise specified, take samples according to GB/T 3186, ISO 3170 or sY/T 5317.

8.2 Place a sufficient amount of sample in a tightly sealed container made of material suitable for the liquid to be drawn, and for safety purposes Make sure that the sample container is only filled with 85% to 95% of its volume.
If the prediction test is performed more than once, the amount of subsample shall be selected and the provisions of 9.1.1 apply.
8.3 Store samples under conditions that minimize vapor loss and increase pressure. Avoid storing samples at temperatures above 30°C.

9 Sample processing

9.1 Petroleum products and fatty acid methyl esters

9.1.1 For subsamples, cool the sample in a cooler or refrigerator (6.5) or warm the sample and its container before opening the container to remove the test sample. Adjust the temperature to at least 10% lower than the first selected test temperature. If an aliquot of the original sample must be stored prior to testing, ensure that the container is still Fill to at least 85% of its capacity. Slowly stir the sample to ensure homogeneity so that the loss of volatile and light components is minimized low degree.
Note: If the volume of the sample falls below 85% of the container capacity, the results of the flash point test may be affected.

9.1.2 For samples that are liquid at room temperature, if the test sample can flow sufficiently, mix the sample by shaking gently by hand before removing the test sample. product, taking care to minimize the loss of volatile components. If the sample is too viscous at room temperature, a heater or oven (6.4) can be used to The sample in the container is heated to 10°C lower than the test temperature. The samples can be mixed with gentle shaking.

9.1.3 A solid or semi-solid sample, if heating according to 9.1.2 does not allow sufficient flow of the test material for injection into the test through the feed hole The test sample can be added to the test cup with a solids dispenser or a flat spoon while the lid is opened.

9.2 Paints, varnishes and related materials

Prepare samples according to GB/T 20777.

10 test steps

10.1 General

10.1.1 Adjust the test temperature to the desired flash point temperature in accordance with the manufacturer’s instructions.

10.1.2 When testing fatty acid methyl esters (FAME), a flash point detector (A.1.6) should be used.

10.1.3 Do not use the test flame to ignite the test sample multiple times. A new test sample shall be used for each test. gas after each test The control valve closes the regulator and test flame. When the temperature of the test cup drops to a safe range, remove the test sample and clean the instrument.

10.1.4 The true flash point should not be confused with the blue halo that sometimes surrounds the test flame before the actual flash at ignition.
Note: The optional flash point detector (A.1.6) is not affected by this halo and does not require the operator to carefully observe the idle point test.

10.1.5 Use the barometer (6.3) to record the ambient atmospheric pressure near the instrument during the test.
Note: Correction of barometric pressure readings to barometric pressure at 0°C need not be taken into account, although some barometers are designed to do this automatically.

10.2 Test procedure for determining the flash point at all temperatures not greater than 100°C and FAME.

10.2.1 Use a clean and dry syringe with a temperature adjusted to at least 10°C lower than the expected flash point to draw 2 mL of the test sample. That is, the sample container is tightly capped to minimize the loss of volatile components.

10.2.2 Carefully move the syringe to the addition hole and inject the test sample into the test cup by fully pushing down the plunger of the syringe. remove the bet shooter.

10.2.3 For solid or semi-solid samples, directly add approximately 2 mL of sample into the test cup and make the sample as homogeneous as possible. Evenly distribute on the bottom of the test cup.

10.2.4 Start the 1 rain timer (A.1.3), open the gas control valve and ignite the test flame, adjust the test flame to a diameter of 4 mm Spherical, if installed flash point detector (A.1.6) reset the detector.

10.2.5 When the audible timing signal sounds, open the shutter slowly and uniformly within 2 s to 3 s, apply the test flame, and then close the shutter, while observing the flash fire (see 10.1). .4).
If a continuous glowing flame burns at the nozzle when the slide is opened and the test flame is inserted, then the flash point is significantly higher than the test flame The temperature is low, in this case, it is recommended to reduce the test temperature by 10 °C.

10.2.6 If a flash fire is observed, repeat 10.2.1 with a fresh test sample starting at a temperature 5°C lower than the temperature at which the flash fire was observed. To the test procedure of 10.2.5. If flash fire is still observed at this lower temperature, reduce the temperature by another 5°C and repeat Test procedure until no flash fire is observed.

10.2.7 If no flash fire is observed, repeat 10.2.1 from a temperature 5°C higher than the previous measurement temperature with a new test sample. To the test procedure of 10.2.5, repeat the test at each 5°C higher interval until a flash fire is observed.

10.2.8 Repeat 10.2.1 to 10.1 for each test with freshly taken test samples starting from the lower temperature point at 5°C intervals as determined in 10.2.6 and 10.2.7, at 1°C intervals. Test procedure 2.5 until a flash fire is observed. Record the temperature readings on the thermometer when flash fires are observed at 1°C intervals. If more precision is required, a temperature 0.5°C lower than the temperature at which flash fires are observed at 1°C intervals can be used to test freshly taken test samples. If no flash fires are observed, the temperature recorded during the 1°C interval test shall be used as accurate Flash point observed at 0.5°C. If a flash fire is observed, this new temperature reading is the observed flash point.

10.3 is greater than lOO. C Test procedure for flash point [except for testing FAME (see 10.2)]

10.3.1 Use a clean and dry syringe (6.2.2) to suck up 4 mL of the test sample, and close the sample container immediately after taking out the sample to prevent volatilization. The loss of sexual components is minimized.

10.3.2 Carefully move the syringe to the addition hole and inject the test sample into the test cup by fully pushing down the plunger of the syringe, removing the syringe.

10.3.3 For solid or semi-solid samples, the equivalent of approximately 4 mL of sample can be added directly to the test cup, and the sample can be distributed as evenly as possible on the bottom of the test cup.

10.3.4Turn on the 2 min timer (A.1.3), open the gas control valve and ignite the test flame, use the throttle valve to adjust the test flame into a sphere with a diameter of 4mm, if a flash point detector (A.1.6) is installed ), reset the detector.

10.3.5 Follow the test procedures in 10.2.5 to 10.2.8 and record the observed flash point.

11 Calculation

11.1 Conversion of Barometric Pressure Readings

If barometric pressure readings are not measured in kPa units, convert to kPa using one of the following formulas
hPa reading × 0.1=kPa
mbar reading × 0.1=kPa
mmHg reading × 0.133 3=kPa
11.2 The observed flash point is corrected to the flash point at standard atmospheric pressure

Use the following formula to calculate and correct the flash point (Tc) at standard atmospheric pressure i01.3 kPa.

T0——the observed flash point at ambient atmospheric pressure, in degrees Celsius (°C);
P—— ambient atmospheric pressure, in kilopascals (kPa).
Note: Only when the atmospheric pressure is in the range of 98.0 kPa ~ 104.7 kPa, the above formula can be accurately corrected.

12 result representation

The report is corrected to the flash point at standard atmospheric pressure, accurate to 0.5°C or 1°C as specified.
Report the test temperature interval (0.5°C or 1°C).
Report the ambient atmospheric pressure near the instrument (see 10.1.5)

13 Precision

13.1 General

The precisions given in 13.2, 13.3 and Table 1 are obtained through experiments on petroleum and related products, FAME products and paints, enamels, spray paints, varnishes and related products with a viscosity of less than 150 mm2/s at 25°C. Statistical analysis of laboratory test results.

13.2 Repeatability Limits r

By the same operator, using the same instrument, under fixed operating conditions, and operating correctly according to the provisions of this test method, only 5% of the difference between the two test results measured on the same sample will eventually exceed the values given in Table 1. value of .

13.3 Reproducibility limit R
By different operators, in different laboratories, operating correctly according to this test method, only 5% of the difference between two separate test results measured on the same sample will eventually exceed the values given in Table 1.

Table 1 Precision Values

ClassificationRepeatability limit/℃Reproducibility limit/℃
Petroleum and related products20℃~70℃Above 70℃
Paints, enamels, spray paints and varnishesViscosity ≤5.8 m㎡/s at 37.8℃Viscosity >5.8 m㎡/s at 37.8 ℃
 Fatty acid methyl ester (FAME)1.915.0
Note: X is the mean of the compared results.

Note: The following values are calculated from the precision values of petroleum and related products in Table 1.

temperature/℃repeatability limit/℃Reproducibility limit/℃

14 Test report

The test report shall at least include the following contents:
a) indicate the number of this standard;
b) Type of product to be tested and complete identification
c) test results (see Chapter 12);
d) any deviation from the prescribed method;
e) Test date.