Some standard content:
National Standard of the People's Republic of China
Petroleum oils-Determination of pour pointUDC 665.7.035.6
GB/T 3535--83
: Confirmed in 1991)
ISO 3016--1974
This method is applicable to the determination of the pour point of petroleum and petroleum products. The lowest temperature at which the sample can flow when cooled under specified conditions is called the pour point.
This method is formulated in accordance with the international standard ISO3016--1974 "Determination of pour point of petroleum", with slight differences in the provisions of coolant, cold bath temperature, sample heating and cooling temperature, pad placement position, and heating temperature for pour point determination. 1 Method Overview
1.1 After preheating, the sample is cooled at a specified speed, and the fluidity of the sample is checked every 3°C. The lowest temperature at which the sample is observed to flow is recorded as the pour point.
2 Instruments
Pour point tester (see figure).
*Inner diameter of casing is larger than test tube
Thermometer
Cork
Outer diameter 9.5～12.5
Inner 30~33.5
2.1 Test tube: cylindrical and flat bottom made of transparent glass. The inner diameter of the test tube is 30.0～33.5 mm and the height is 115～125 mm. There is a long scale mark at the 45 ml volume of the test tube, and short scale marks are also marked 3 mm above and below the scale mark to allow the sample volume to fluctuate. 2.2 Thermometer (see Appendix A for details):
National Bureau of Standards 1983-03-09 Issued
1983-12-01 Implementation
GB/T3535--83
2.2.1 High cloud point and high pour point thermometer: temperature range -38~50℃, graduation value 1 (2.2.2 Low cloud point and low pour point thermometer: temperature range -80~20℃, graduation value 1, 2.3 Cork stopper: used with test tubes, the center of the stopper has a hole for inserting the thermometer. 2.4 Sleeve: made of glass or metal, cylindrical, flat bottom, watertight. It is about 115 mm high. The inner diameter is 9.5~12.5 mm larger than the outer diameter of the test tube.
2.5 Disc: made of cork or felt, 6 mm thick, with the same diameter as the inner diameter of the sleeve. 2. 6 rings: annular, 5 to 6 mm thick, made of cork, felt or other appropriate materials, it is required to be elastic so that it fits tightly against the outside of the test tube, but is loose and wide against the inner wall of the sleeve; at the same time, it must be hard enough to maintain its shape. The purpose of the gasket is to prevent the test tube from contacting the sleeve.
2.7 Cold bath: The type must be suitable for obtaining the specified temperature requirements. The size and shape can be selected arbitrarily, but the sleeve must be firmly fixed in a vertical position. To determine the pour point below 10°C, more than two cold baths are required. The bath temperature can be maintained by freezing or a suitable coolant.
Note: "· Generally speaking, water and ice are used above 0°C, and industrial ethanol and dry ice (or liquid nitrogen, etc.) are used below -15°C. Other refrigeration methods can also be used to achieve the required bath temperature.
3 Test steps
3.1 Pour the clean sample into the test tube to the mark. For viscous samples, heat them in a water bath until they become fluid and then pour them into the test tube. Note: If the sample was heated to a temperature higher than 45°C 24 hours ago, or if the heating conditions are unknown, keep the sample at room temperature for 24 hours before testing. 3.2 Tightly plug the test tube with a cork plugged with a high cloud point and high pour point thermometer. If the pour point is higher than 39°C, the thermometer used is as in Note ①. Adjust the position of the cork and thermometer so that the cork plugs the test tube tightly, the thermometer and the test tube are on the same axis, and the mercury ball of the thermometer is immersed so that the starting point of the capillary of the thermometer should be immersed 3 mm below the sample liquid surface as in Note ②. Note: ① When measuring samples with a pour point higher than 39°C, it is allowed to use any thermometer in the range of 32 to 105°C. It is recommended to use a 0.5°C ② Before the test, the freezing point of the thermometer should be verified. If the freezing point deviates from 0℃ and exceeds 1℃, it should be further inspected or recalibrated. 3.3, the sample in the test tube is pretreated as follows: 3.3.1 The pour point of the sample is between 33 and -33℃. Without stirring the sample, place the sample in a 48±1℃ water bath and heat it to 45±1℃. Cool the sample to 36±1℃ in air or a water bath of about 25℃, and then continue the test according to 3.4 of this method. 3.3.2 The pour point of the sample is higher than 33℃
Without stirring the sample, place the sample in a 48±1℃ water bath and heat it to 45±1℃ or to a temperature about 9℃ higher than the expected pour point temperature (see Note ① of 3.2 of this method), whichever is higher, and then continue the test according to 3.4 of this method. 3.3.3 The pour point of the sample is lower than -33℃
Heat the sample according to 3.3.1 of this method, and then place it in a water bath at 7±1℃ to cool to 15±1℃. Remove the high cloud point and high pour point thermometers and replace them with low cloud point and low pour point thermometers. Continue the test according to 3.4 of this method. 3.4 The disc, gasket and sleeve should be clean and dry inside and outside. Place the disc at the bottom of the sleeve. Place the gasket about 25 mm above the sample liquid surface in the test tube. Place the test tube in the sleeve. 3.5 Keep the temperature of the cold bath at -1~2℃. Stably install the sleeve with the test tube in a vertical position in the cold bath so that the sleeve is not more than 25 mm above the cooling medium liquid surface.
3.6 After the sample has been cooled sufficiently, paraffin crystals will form. Be very careful not to stir the sample and the thermometer, and do not allow the thermometer to move in the sample. Any disturbance of the sponge network of paraffin crystals will lead to low or untrue results. 3.7 For samples with a pour point higher than -33°C, the test starts at 9°C above the expected pour point, and for samples with other pour points, the test starts at 12°C above the expected pour point. Whenever the thermometer reading is a multiple of 3°C, carefully remove the test tube from the sleeve and tilt the test tube until you can just observe whether the sample in the test tube flows. The entire operation from removing the test tube to putting it back should not exceed 3 seconds. If the temperature has dropped to 9°C. If the sample still flows, move the test tube to the sleeve of the second cold bath maintained at -18 to 15°C (see Note). If the temperature has dropped to -6°C and the sample still flows, move the test tube to the sleeve of the third cold bath maintained at 35 to -32°C. 333
GB/T3535---83
When additional baths are required to determine extremely low pour points, the temperature of each bath should be maintained at 17°C lower than the temperature of the previous bath (the following bath temperatures are -52 to 49°C, 69 to -66°C and -86 to 83°C, etc.). Whenever the sample temperature reaches above When the temperature of the new bath reaches 27°C (the following transfer temperature sequence is -24°C, -42°C and -57°C, etc.), the test tube should be transferred (see note), but the cold test tube should never be placed directly in the cooling medium. When the test tube is tilted and the sample does not flow, immediately place the test tube in a horizontal position and carefully observe the surface of the sample. If there is still flow within 5 seconds (which can be measured with a stopwatch or other accurate timer), immediately put the test tube back into the sleeve and repeat the flow test when the temperature drops by another 3°C.
Note: The sleeve can remain in the bath or move with the test tube. 3.8 Continue according to the above steps Continue the test until the test tube remains in a horizontal position for 5 seconds without the sample flowing, and record the observed test thermometer reading.
3.9 For dark oils, cylinder oils and non-distillate fuel oils, the steps described in 3.1 to 3.8 of this method are followed, and the result obtained is the upper (highest) pour point (see note). If necessary, the sample can be heated to 105±1℃ while stirring, poured into the test tube, cooled to 36±1℃ as described above, and the lower (lowest) pour point can be measured according to the steps described in 3.1 to 3.8 of this method. Note: When it is known that the sample was heated to a certain temperature above 45℃ 24 hours ago, If the temperature is unknown, or the heating process is unknown, the sample shall be heated to 100±1℃ before the test and then kept in a room for 24 hours. 4 Calculation
The temperature recorded in 3.8 of this method plus 3℃ shall be used as the pour point of the sample. 5 Precision
The reliability of the test results shall be judged by the following provisions (95% confidence level). 5.1 Repeatability
The difference between two results determined repeatedly by the same operator shall not exceed 3℃. 5.2 Reproducibility
The difference between two results proposed by two laboratories shall not exceed 6℃. 5.3 Special circumstances
According to 3.9 The method described above is not suitable for determining the pour point of the sample. This reproducibility is not suitable because the pour point of these samples will show abnormal phenomena as their heating history.
Note: This precision was obtained by conducting statistical tests on 6 samples in 9 laboratories in 1982, and processing and analyzing the test results. 6 Report
The arithmetic mean of two repeated results is taken as the pour point. For black oil, etc., the results are reported as upper pour point or lower pour point as required. 331
Immersion depth
Fine scale
Sub-scale
Digital scale
Scale error does not exceed
Expansion chamber, allowed to be heated tobZxz.net
Distance from the bottom of the ball to the scale line
Distance from the bottom of the ball to the scale line
Additional instructions:
GB/T 3535
Appendix A
Thermometer Specifications
(Supplement)
High Cloud Point and High Pour Point
-38~50℃
108mm
100℃
230±5mm
7～8mm
7.0~9.5mm
5.5～7.0mm
To-38℃
120～130mm
To 50℃
195~205mm
Low Cloud Point and Low Pour Point
- 80 ～20℃
76mm
1℃(-33℃ and above)
2℃(below-33℃)
230±5mm
7～ 8mm
8.0~9.5mm
5.0~6.5mm
To 57℃
120~130mm
To 20℃
182~196mm
This standard is proposed by the Ministry of Petroleum Industry of the People's Republic of China and is under the jurisdiction of the Petrochemical Research Institute. This standard was drafted by the Petrochemical Research Institute. 335
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