The method of estimating the sedimentation stability of engine oils

 

(57) Abstract:

The invention is intended for use in studies of lubricating oil in the oil refining and other industries in forecasting the timing of the storage of motor oils. As informative parameters use the base number and kinematic viscosity. Centrifugation is carried out for 80,5 h with separation factor 20000100 units, followed by sampling of all tubes. Samples are mixed, determine the base number and kinematic viscosity of the mixture. Sedimentation stability estimate for a consolidated index, defined as the square root of the product of the relative velocity change base number and kinematic viscosity during centrifugation. The application of the method allows you to quickly and reliably estimate the sedimentation stability of engine oils at low cost. 5 table.

The present invention relates to the field of study of lubricating oils, in particular to the estimation of the sedimentation stability of engine oils, and can be used in oil refining and other industries in forecasting the reduction of the potential energy of the particles during settling under gravity /1 - Fredriksberg D. A. Course of colloid chemistry. -L.: Chemistry. -1984. S. 368 /.

The objective of the study was to develop a rapid method to reliably determine the sedimentation stability.

Physical and colloidal stability describes the ability of the oil to keep in the process of storing it in the real terms of the original physical condition.

For the rapid assessment of physical and colloidal stability of oils with additives there are a number of methods based on visual and physico-chemical evaluation of the changes in the oil after a certain period of storage with the use of heat treatment and centrifugation of specimens tested oils.

There is a method of testing time greases on the colloidal stability /2 - GOST 7934.4-74 Lubrication time. Test method for colloidal stability./

The essence of the method consists in determining the sustainability of lubrication to the delamination and separation of the precipitate. To determine the colloidal stability of the applied laboratory centrifuge CKP-3, providing a separation factor of up to 8000 units.

The centrifuge defined tubes include and display for speed and time, predismissal the presence of stratification or sedimentation.

The main disadvantage of this method is that it does not give a quantitative assessment of changes in the qualitative condition of the oil after the test.

Also known a method of evaluating the stability of lubricating oils during storage /3-Bulgarian State standard N 14348-77. Method of assessing the stability of the oil during storage/.

The essence of this method lies in the creation of heavy oil ageing by heating it to 150oC, subsequent centrifugation after reaching room temperature, cooling to the temperature of solidification and re-centrifugation after reaching room temperature. After completing these operations, the oil stored in glass containers within 60 days in a dark place at room temperature. After the test, visual assessment of oil on the presence of sediment. For tests used laboratory centrifuge, providing a separation factor of 1000 units.

The disadvantages of this method is that in addition to the lack of quantitative assessment of changes in quality of the oil condition, it is also time consuming.

The closest technical solution to an alleged invention and taken what's oils /4 - The decision of the state Commission for testing fuels, oils, lubricants and special fluids when Gosstandart N 23/1-79 from 17.03.80. Method qualification physical stability of the transmission and gear oils./.

The essence of this method lies in keeping the sample oil at a temperature of 1005oC for 24 hours, cooled to room temperature (18-22oC) keeping the sample oil at a temperature of minus 202oC for 24 hours and subsequent storage in a dark place at room temperature for 10 days. Thereafter, the sample oil is centrifuged for 30 minutes at the separation factor 500050 units and the stability of the oil is estimated by the change in the value of indicators (critical load, the load welding, the spot diameter of the wear index bully), characterizing extreme-pressure and antiwear properties of the upper and lower layers of the oil after centrifugation.

The disadvantages of this method are its duration, complexity and unacceptability for motor oils specified performance indicators to assess changes in their quality after testing.

The technical result of the invention is efficiency, reducing tradspool determine the sedimentation stability of engine oils on the mismatch of informative parameters, measured before and after centrifugation of the samples, placed in n tubes according to the present invention as informative parameters use the base number and kinematic viscosity, centrifugation is carried out for 8 (0,5) hours factor separation 20000100 units, followed by sampling of all tubes, mix these samples, determine the base number and kinematic viscosity of the mixture, and sedimentation stability estimate for a consolidated index, defined as the square root of the product of the relative velocity change base number and kinematic viscosity during centrifugation.

The essence of the method consists in the following. Given that the engine oils of different grades of viscosity and operational groups it is difficult to reliably estimate the sedimentation stability due to a low rate of sedimentation in motor oils under normal conditions, in laboratory tests using a centrifuge with a large separation factor, sampling oil from the centrifuge tubes with different levels and a subsequent assessment by the misalignment of the source and measured after centrifugation informative is>/P>In the proposed method of estimating the sedimentation stability of engine oils to centrifugation determine the base number (Yabout) and kinematic viscosity (o) the original sample of oil, put it in n tubes, centrifuged within 8 (0,5) hours (factor ) separation centrifuge 20000 100 units, followed by sampling of all the tubes from the upper level, mixed samples, determine the base number (Ywithand kinematic viscositycmixture and of the sedimentation stability of the oil is judged by the following dependencies:

< / BR>
where Kwithis a generalized measure of the sedimentation stability of engine oils;

Kythe relative rate of change base number determined by the formula:

< / BR>
Kthe relative rate of change of kinematic viscosity, defined by the formula:

< / BR>
For testing has been used laboratory centrifuge, table top type T-24 /maintenance manual for the centrifuge T-24 production company "VEB MLW Zentrifugenbau Engelsdorf", 16.11.82,/, providing separation factor 20000 100 units/tubes for a centrifuge with a capacity of 10 ml.

The sampling tubes (12 pieces) was made in this case with percentagedone ( ) and separation factor (f)) conducted studies on oil M-8D2To, which is composed of a significant amount of additives (10%) and has a low viscosity (80,5 mm2/s).

The results are given in table.1 (see the end of the description)

The table shows that with increasing values of the separation factor over f= 20000100 units and centrifugation time more = 0,8 0,5 h the change in Kwithinsignificant and, therefore, these parameter values are optimal for motor oils.

To check the options selected for tests conducted studies samples of commercial motor oils various operational groups and the viscosity. The results are given in table.2 and 3.

From table. 2 shows that for all samples of oils is the most optimal mode of centrifugation of the separation factor f = 20000 100 units.

From table. 3 shows that for all samples of oils is the most optimal mode centrifugation within 8,0 0,5 h

Thus, the optimal operation parameters are the centrifugation time =8(0,5) hours in a centrifuge, providing the separation factor f=20000100 units.

The method is implemented as education is g KOH/g) and kinematic viscosity (o= 7,53 mm2/s) of the original sample. Fill n = 12 test tubes 10 ml, put them in the centrifuge rotor T-24, providing separation factor 20000100 units, centrifuged for 8 (0,5) hours ( ), and then takes samples (3 ml) of all tubes from the upper level with a syringe, mixed samples, determine the base number (Ywith=6.73 x mg KOH/g) and kinematic viscosity (c= 7,46 mm2/s) mixture.

Determine the relative rate of change base number:

< / BR>
Determine the relative rate of change of kinematic viscosity:

< / BR>
Define a generalized index of the sedimentation stability of engine oils:

< / BR>
Getting the value of the overall indexwiththis sample oil M-8D2to and comparing it with a value of Kwithreference oil of this brand, you can judge the sedimentation stability of the sample oil. The higher the value of Kwiththe more oil prone to sedimentation are included in the additives (drop them in the sediment) and the less time the oil can be stored.

In this way samples were studied commodity motor oils, the test results are presented in table. 4 (see end described the La can be distinguished depending on their belonging to different operational groups (a to E) and groups of viscosity (from 8 to 20 mm2/c). The higher the value of Kwiththe oil has a lower sedimentation stability. So oil M-16G2CA (group G) is more stable compared to oil M-8D2for (group G), having a lower viscosity, and oil M-K (group D) having the same viscosity, but containing a greater amount of additives. Thickened oil (M-63/10B2M-(63/10V) are even less sediment stability in relation to nezapomenem oils, at the same time, depending on the membership of the operational group also differ in the sedimentation stability. So, with the same viscosity oil M-63/10B (group b), contain more additives than oil M-63/10B2(group B), has the value Kwithabove and, therefore, less sedimentation stability.

Thus, examining a considerable number of samples of commercial motor oils, the authors state:

- oils have the same viscosity with increasing content of a number of additives belonging to the higher operational group) have a higher value of the complex indexwithand, therefore, less sedimentation steadily the number of additives), with increasing viscosity of less importance of the complex indexwithand, hence, greater sedimentation stability;

- thickened oils have a higher value of the complex indexwiththan nezahodnye and, therefore, less sedimentation stability;

- comparing the value of the complex indexwitha sample of the engine oil with the value of the complex indexwithoils of the same brand, taken as a standard, it is possible to draw the conclusion about the sedimentation stability of the sample oil and the possibility of its long-term storage.

The inventive method in addition to reliability (table. 4) helps to lower labor costs in the operational definition of the sedimentation stability of engine oils (table. 5).

Comparative analysis of the results of the test oil by the present method and the method prototype is presented in table. 5.

From table. 5 shows that the proposed method significantly outperforms the method prototype for efficiency (29 times), complexity (fewer operations) with a significant increase in accuracy (2.5 times).

Thus, the claimed method meets the requirements of patentable is th number and kinematic viscosity, characterize the sedimentation stability of engine oils);

- non-obviousness (authors when viewing patent information, scientific and technical literature is not found above essential features - the use of the generalized parameter Kwithreflecting the relationship of the base number and kinematic viscosity of the sample oil is measured before and after centrifugation);

industrial applicability (the method is simple, rapid and implement planned his introduction to the interagency methods for the prediction of shelf-life motor oils in Q1 - 1998).

The use of the invention will promptly and reliably assess the sedimentation stability of engine oils at low cost method.

Sources of information:

1.Fredriksberg D. A. Course of colloid chemistry. -L.:Chemistry.-1984.- S. 368.

2. GOST 7934.4-74 Lubrication time. Test method for colloidal stability.

3. Bulgarian State standard N 14348-77. Method of assessing the stability of the oil during storage.

4. The decision of the state Commission for testing fuels, oils, lubricants and special fluids when Gosstandart N 23/1-79 from 17.03.80. Method qualification tentazioni stability of engine oils on the mismatch of informative parameters, measured before and after centrifugation of the samples, placed in n tubes, characterized in that as informative parameters use the base number and kinematic viscosity, centrifugation is carried out for 8 0.5 h with a separation factor 20000 100 units, followed by sampling of all tubes, mix these samples, determine the base number Wwithand kinematic viscositycto the mixture, and sedimentation stability estimate for a consolidated index TOaboutdetermined by the formula

< / BR>
where Kythe relative rate of change base number during centrifugation, defined by the formula

< / BR>
Kthe relative rate of change of kinematic viscosity during centrifugation, defined by the formula

< / BR>
W0,ovalue base number and kinematic viscosity prior to centrifugation;

the time of centrifugation.

 

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