definition
When the oil sample is cooled under the conditions specified by the standard, the lowest temperature at which the oil can continue to flow is called the pour point.
The maximum temperature at which the oil sample is cooled under the specified test conditions until the liquid level does not move is called the freezing point.
significance
The freezing point or pour point of lubricating oil is an important quality indicator for its low temperature fluidity.
Lubricating oil with high pour point or high freezing point cannot be used at low temperature. Otherwise, the lubricating oil will lose its fluidity at low temperature and block the oil circuit, which cannot guarantee lubrication. For engine oils, low temperature start-up is difficult due to the high pour point or pour point. Therefore, it is generally preferred to use a lubricating oil having a pour point or a pour point lower than the use temperature by 10 to 20 ° C.
In addition to the pour point or pour point of the lubricating oil, the low temperature viscosity of the lubricating oil should also be considered.
Petroleum products are complex mixtures of many hydrocarbons, each of which has its own freezing point, so when the temperature is lowered, the oil does not solidify immediately, going through a thickening stage and gradually solidifying at a relatively wide temperature. Therefore, the pour point of the same sample is about 3~5 °C higher than the pour point. The reason why the waxy oil loses fluidity at low temperature is because the high melting point paraffin hydrocarbon (except normal hydrocarbons, which contains a small amount of isomeric and cyclic hydrocarbons) precipitates in the form of needles or flakes and bonds to each other. A three-dimensional network structure is formed, and the low melting point oil is adsorbed and encapsulated therein, resulting in loss of fluidity of the entire oil.
There are two ways to reduce the pour point of waxy oils:
First, deep dewaxing of the base oil can obtain low pour point lubricating oil, so that the yield of the oil is low, the cost is high, and at the same time, a large amount of normal hydrocarbons are removed, and the quality of the oil is also damaged;
The second is to carry out moderate dewaxing, then add pour point depressant to reach the required pour point. The pour point depressant cannot prevent the paraffin hydrocarbons from crystallizing at low temperature, but prevents the paraffin hydrocarbons from forming three-dimensional network crystals and losing fluidity by adsorption or eutectic action. Different lubricating oils have different sensitivities to pour point depressants, and insufficient or excessive amounts can not achieve the desired pour point depressing effect. Measurement method The determination of the pour point is carried out according to the standard method of GB/T 3535-83.
This standard is equivalent to ISO 3016-1974. After the sample was preheated, it was cooled at a prescribed speed, and the flowability of the sample was checked every 3 ° C, and the lowest temperature at which the sample was able to flow was recorded as a pour point. The repeatability of the method is that the same operator repeatedly measures the difference between the two results not exceeding 3 °C. Reproducibility is: the difference between the two results proposed by the two laboratories does not exceed 6 °C. The determination of the freezing point is carried out according to the standard method of GB/T 510-83. At the time of measurement, the sample was placed in a predetermined test tube, and when cooled to a desired temperature, the test tube was tilted by 45°, and after 1 minute, it was observed whether the liquid level moved. Record the highest temperature at which the liquid level in the test tube does not move as the freezing point. The repeatability of the method is that the same operator repeatedly measures the difference between the two results not exceeding 2 °C. Reproducibility is: the difference between the two results proposed by the two laboratories does not exceed 4 °C.
The freezing point measuring instrument is designed and manufactured in accordance with the provisions of the People's Republic of China standard GB/T510 "Petroleum product freezing point determination method". The instrument adopts new type of compressor, advanced digital temperature controller and unique cooling bath. It has good refrigeration effect, high temperature control precision and uniform and stable cold bath temperature. It is suitable for oil production, production and use units. Schools, scientific research departments, etc. for the determination of the freezing point of petroleum products.
It adopts modern high-tech microelectronic control technology, combined with semiconductor refrigeration technology. The automatic freezing point measuring instrument adopts MCS-51 series single chip microcomputer as the system control core, color liquid crystal display, Chinese man-machine dialogue, guided operation, and the measurement process is fully automated (automatic Refrigeration temperature control, automatic detection), automatic analysis of samples. The whole automatic freezing point measuring instrument is advanced in design, reasonable in structure, simple in operation, safe and reliable. It is the most complete automatic point/pour point tester with the same technical level and performance index of similar products at home and abroad. It is suitable for refineries, electricity, The determination of the pour point/pour point of light oil by railway, shipping, oil company and oil commercial department. The measurement result conforms to the national standard GB510-83 "Measurement method of petroleum product freezing point" GB3535-83 "Petroleum Pour Point Determination Method" Regulation
Instrument features:
Automatic freezing point tester (pour point tester) test speed
2, the result is accurate
3, good repeatability
4, stable and reliable
5, easy to operate, and combined with modern new process methods.
Beijing Heng Aode Instrument & Meter Co., Ltd. specializes in water quality detector, coating thickness gauge, soil pulverizer, tempered glass tester, water quality tester, PM2.5 tester, inhalable particulate matter detector, high frequency heat sealing machine, Strain control triaxial apparatus, milk somatic cell detector, helium gas concentration detector, soil moisture conductivity tester, field strength meter, collection box, color ratio measuring instrument, capillary water absorption time measuring instrument, oxidation reduction potentiometer Instrument, carbon monoxide carbon dioxide detector, CO2 analyzer, oscillopolarograph, slime content tester, car starter power supply, automatic potentiometric titrator, portable thermometer, zirconia analyzer, reed switch tester, precision conductance Rate meter, TOC water quality analyzer, microcomputer plasticity measuring instrument multi-function chloride ion analyzer, chlorophyll stainless steel water sampler extruder, drug freezing point, the company adhering to the "customer first, forge ahead" business philosophy, adhere to the "customer first" The principle of providing quality services to our customers. Welcome patrons!
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