The way to determine the hydrolytic stability of engine oils

 

The method is applicable in the field of chemmotology at motor oils for the selection of the additives in the development of new oils and evaluate the quality of the oils during prolonged storage. The method includes taking a sample of oil, making water, heating, centrifugation with subsequent determination of base number and the evaluation of the hydrolytic stability of the oil, and after taking a sample determine the base number of the original oil, add 5% water, homogenize the oil with water and provide heating at 902oC for 1 h, centrifuged at separation factor 400040, and hydrolytic stability of the oil is judged based on SC1-SC2ToSCwhere SC1and SC2respectively the values base number of the original oil and oil after heating and centrifugation,SC- criterion hydrolytic stability under alkaline. 8 table.

The present invention relates to the field of chemmotology at motor oils and can be used in research laboratories petroleum refining industry for the selection of the additives in the development of new oils, political stability, including the capture of sample, making 25% of water, heated at a temperature of 100oC for 48 hours in the presence of a catalyst, a copper plate with a subsequent assessment of the degree of hydrolysis of change of viscosity, acid number and corrosion of the copper plate (Chernov, K. S. , Sivina R. K., Kozlov, H. N., Kaverin N.And. The study vlagopoglascheniem and hydrolytic stability of aviation oils for GTE in HTM, 1969 10, s 50...53).

The disadvantages of this method is the duration, the absence of a stage of homogenization of the mixture of oil and water do not simulate operational conditions.

There is a method of determining the hydrolytic stability of the oils is taken as a prototype, including the capture of sample oil, making 15% of water, mixing, heating at a temperature of 110oC for 4 hours, diluted with gasoline and centrifugation at the separation factor 6000 with subsequent determination of total alkalinity of the sample (Gabsatarova S. A., Glavati O. L., Rabinovich, I. A. and others, evaluation of the stability of the colloidal dispersion of alkali sulfonated and alkylsalicylate additives. Refining and petrochemicals. Issue 11. - Kiev: Naukova Dumka, 1974, S. 7...10).

The disadvantages of this method is the duration of the test, the absence of agnosti evaluation of hydrolytic stability, as in the way that there are no boundaries and criteria for determining hydrolytic stability.

The present invention solves the problem of increasing the reliability of the determination of hydrolytic stability of engine oils and reduce the time of analysis.

This object is achieved by the proposed method for the determination of hydrolytic stability, including the capture of sample oil, making water, heating, centrifugation with subsequent determination of base number and the evaluation of the hydrolytic stability of the oils, but after taking the sample determine the base number of the original oil, add 5% water, homogenized oil with water and carry out the heating at a temperature of 902oC for 1 hour, centrifuged at separation factor 400040 and hydrolytic stability of the oil is judged based on SC1-SC2ToSC(1) where SC1; SC2respectively the values base number of the original oil and oil after heating and antipyrine, KSC- criterion hydrolytic stability under alkaline.

The proposed method differs from the method of the prototype the following. After in the process is heated at a temperature of 902oC for 1 hour, centrifuged at separation factor 400040 and hydrolytic stability of the oil is judged based on SC1-SC2ToSCwhere SC1; SC2respectively the values base number of the original oil and oil after heating and centrifugation:SC- criterion hydrolytic stability at alkaline, These characteristics are essential for solving the problem of the invention as motor oils, usually ash additives, have basic properties and, for them, an important characteristic indicator is the base number. This indicator is able to indirectly reflect the cumulative effect of the processes of solubilization and hydrolysis. By changing the base number of the oil can be judged from changes in the ash content, pH, loss of active metal additives, etc. In the developed method, the base number is selected as the estimate.

To select test conditions, their theoretical justification for studying the influence of various factors on the stability of engine oils when exposed to water experimental research. In table. 1 shows the effect knii from 1 to 5% water and the degree of decomposition of the additives is very noticeable, further, when a larger (5%) concentration change of this index (base number) is insignificant. Thus, in the proposed method, the concentration of water is taken 5%. After making water in oil is a mixture homogenized. Using the homogenizer speed is not less than 5 thousand min-1or other mixing device, providing a uniform emulsion. Homogenization of the mixture allows to estimate the influence of water on the average of all the oil.

With increasing temperature up to 90oWith system oil-additive-water (PL. 2) there is a significant reduction of the estimated indicator, then this change slightly to 110oSince At temperatures above 110oWith a sharp decrease of base number of the oil, which apparently is associated with increased oxidative process transformations oils and additives. By the well-known rule Vant Guff temperature increase of 10oC accelerates the oxidation reaction in 2-3 times (Theoretical foundations of chemmotology at. Edited Bratkov A. A. - M.: Chemistry, 1985, 320 C.). Therefore, when assessing the impact of water on the quality of the oils necessary to maintain low temperature in order to eliminate the influence of oxidation products and actuation p of the table.3, the exposure time of the water in the butter for 1 hour is optimal for this time occur mainly basic processes (solubilization and hydrolysis). A further increase in time does not lead to a significant change base number of the oil and impractical.

Centrifuged oil after heating when the separation factor (FR) 400040. FR is determined by the formula FR=11210-5r n2,
where r is the maximum radius from the axis of the centrifuge rotor to the extreme point of the bottom of the rotating tube, m:
n is the rotational speed of the centrifuge rotor, min-1.

The optimum separation factor centrifugation authors chosen empirically. Centrifugation of oil with 5% of water at different separation factors showed that a significant reduction in base number observed in FR 400040, and with further increase of the FOA does not lead to a noticeable reduction of the base number.

In addition, FR 400040 close to the maximum separation factor of centrifuges modern engines.

On the hydrolytic stability of the oil is judged based on SC1-SC2ToSC.

This dependence is needed on the mistakes is the lack of clear boundaries stability, i.e. when the oil is stable, and when not.

The authors have conducted preliminary tests on the hydrolytic stability of several oils. The data obtained are given in table.4.

As can be seen from the data table.4, the values of the base number of tested oils differ significantly from the values in the original. In this regard, as noted above, it is necessary to set the acceptable level of difference between the indicator "SC" of the original oil and the same oil after the test.

For this we have used the criteria ToSCthat characterizes the maximum permissible error of oil analysis results. This came from the fact that if the difference between the values SC" obtained for the original oil and the same oil, tested for stability, not To exceedSCthen each of the matched results (SC) shows the same desired value and the oil is considered to be hydrolytically stable, i.e. SC1-SC2ToSC.

If the difference between the mapped results of the estimated indicator of more ToSCit indicates a qualitative change in the level of oil properties after exposure to water, heat and centrifugation, the comprehension ToSCis

wherethe coefficient of variation,
n is the number of parallel measurements (taken equal to 2),
- the average of the determined values (SC1original oil
- the same oil after territoriaalne (i.e., after the test) (Alekseev, R. I., Korovin Y. I. guidance on the calculation and processing of the results of the quantitative analyses. - M.: Atomizdat, 1072, s.).

In this formula, the coefficient of variation is accepted calculation and experimental way. Moreover, the coefficient of variation was calculated by previously accumulated analytical data for two samples of oil M - 63/10 - In and 10P MTW, which differ significantly from each other alkaline. The level of changes in alkaline number of other oils lies within or close to the values typical for these oils.

The coefficient of variation (v) was determined and calculated according to a study (20 parallel definitions).

In this description to give a final settlement and adopted by the coefficients of variation (table. 5).

As can be seen from the table.5, finally for the metric SC adopted from the cylinder the proposed method dependencies (1) and criteria ToSCallows to increase the reliability of determination of hydrolytic stability and high precision of the estimate. This dependence is not related to a mathematical treatment of the results (although at first sight is a mathematical dependence), i.e. in the absence of the reliability and accuracy of the method is excluded and nothing to talk about stability becomes meaningless.

Thus, all the characteristics mentioned in the claims, are required in combination to achieve the objectives of the invention.

The method is as follows. The source of the oil determine the base number (SC1in accordance with GOST-1 1362-76. Then in a glass homogenizer fill in the test oil 50 g with an accuracy of 0.1 g and contribute 2.5 g of distilled water (5%) with accuracy of 0.1 was Homogenized with 5 thousand min-1within 10 minutes. Next, in a clean chemical glass pour the emulsion of water in oil and placed in a thermostat heated to 902oC. Stand the test oil for 1 hour. After heating the glass removed from thermostat and from the upper layer (without mixing), cast in a test tube centrifuge the required amount of oil. Then centrifuged to test the tubes using a syringe to take away the top layer of the test oil and determine the base number (SC2) according to GOST 11362-76.

Further, according to the data obtained SC1and SC2expect criterion ToSCby the formula (4) and hydrolytic stability of the oil estimate based on
SC1-SC2ToSC.

If the difference is smaller thanSCthe oil is hydrolytically stable.

An example of specific performance
The claimed method was studied hydrolytic stability of a number of motor oils according to the described method. The data obtained are given in table. 6.

As can be seen from the table.6, lubricants M-16-B2, MTZ-10p, M-z/10-B1turned out to be hydrolytically unstable, it confirms the practice of applying oils on the technique and experience of their storage, i.e., when the flooding they lose their operational properties. In addition, the study of literature data about the persistence of a separate additive to the effects of water confirm the results obtained. So part of hydrolytically unstable oils are metastabile additives VNII MP-360 and Tits FE-22k. Determination of the hydrolytic stability was also carried out using the prototype method. Summarised in table. 7.

As can be seen from the table. 7, when using protot the th alkalinity oils are not stable or stable, talking about it is difficult, i.e. it is only possible to compare the stability of one oil with another. Thus, it is possible to conclude about the low reliability of the prototype method.

When using the proposed method reduces the time of the evaluation hydrolytic stability of oils compared to prototype more than 2.5 times (table. 8).

Thus, from the above material suggests that technical and economic effect of the proposed method of determining the hydrolytic stability of engine oils is to increase the reliability of the determination and reduction of analysis time.

Sources of information
1. Chernov, K. S., Sivina R. K., Kozlov II.II., Kaverin N.And. The study vlagopoglascheniem and hydrolytic stability of aviation oils for GTE in HTM, 1969, 10, s 50...53.

2. Gabsatarova S. A., Glavati O. L., Rabinovich, I. A. and others, evaluation of the stability of the colloidal dispersion of alkali sulfonated and alkylsalicylate additives. Refining and petrochemicals. Issue 11. - Kiev: Naukova Dumka, 1974, S. 7...10 (prototype).

3. Theoretical foundations of chemmotology at. Edited Bratkov A. A. - M.: Chemistry, 1985, 320 S.

4. Alekseev, R. I., Korovin Y. I. guidance on the calculation and processing of the results of the quantitative analyses. - M.: Atomic is innosti motor oils, including the capture of sample oil, making water, homogenization of the oil with water, heating, centrifugation and determination of the base number of the oil, characterized in that after the taking of the sample determine the base number of the original oil, add 5% water, conduct heated at 902oC, centrifuged at separation factor 400040 and evaluate the hydrolytic stability of the oil by difference alkaline numbers of the original oil and oil after the test, which must be less than or equal to the criterion hydrolytic stability, defined by the formula

where- coefficient of variation;
n is the number of parallel measurements, equal to 2;
- the average of the determined values base number, respectively, of the original oil and oil after the test.

 

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