1、October 2004DEUTSCHE NORM English price group 6No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 75.100!$R:m“1472374w
2、ww.din.deDDIN 51453Testing of lubricants Determination of oxidation and nitration of used motor oils Infrared spectrometric methodPrfung von Schmierstoffen Bestimmung der Oxidation und Nitration von gebrauchten Motorenlen Infrarotspektrometrisches Verfahrenwww.beuth.deTranslation by DIN-Sprachendien
3、st.In case of doubt, the German-language original should be consulted as the authoritative text.Document comprises 6 pagesDIN 51453:2004-10 2 Foreword This standard has been prepared by Technical Committee NMP 663 Gebrauchtl-Untersuchung of Technical Department Minerall- und Brennstoffnormung of the
4、 Normenausschuss Materialprfung (Materials Testing Standards Committee). 1 Scope This standard applies to used petrol and diesel engine oils. Whether it can be applied to other oils is currently being checked. The method described serves to determine the extent of oxidation and nitration in used eng
5、ine and gear oils by measuring the absorption of infrared light of certain wavelengths using fresh oil of the same type as a reference. The values obtained are a measure of the ageing of the oil. Evaluation of the oxidation is made difficult or impossible if the oil contains more than 3 % soot; if i
6、t contains ester-based additives or if the oil itself is ester-based; if it is used with biodiesel (i.e. FAME (fatty acid methyl ester); if it is a mixture. The aromatic band at 1 600 cm1, which is due to factors such as contamination with fuel, interferes with the evaluation of nitration. 2 Normati
7、ve references This standard incorporates, by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text, and the titles of the publications are listed below. For dated references, subsequent amendments to or revisions of
8、 any of these publications apply to this standard only when incorporated in it by amendment or revision. For undated references, the latest edition of the publication referred to (including amendments) applies. DIN 51451, Analysis of mineral oil products and related materials by infrared spectroscop
9、y General principles DIN 51574, Sampling of lubricating oils taken from internal combustion engines DIN EN ISO 3170, Petroleum liquids Manual sampling (ISO 3170:2004) DIN EN ISO 4259, Petroleum products Determination and application of precision data in relation to methods of test (ISO 4259:1992 + C
10、or. 1:1993) DIN 51453:2004-10 3 3 Terms and definitions For the purposes of this standard, the following terms and definitions apply. 3.1 oxidation during use, engine oils are oxidized by entrained oxygen. The oxidation products can be determined as a group from the relative attenuation of infrared
11、light at a characteristic wave number of 1 710 cm1. 3.2 nitration during use, engine oils are nitrated by the nitrogen oxides produced by the combustion process. The nitration products can be determined as a group from the relative attenuation of infrared light at a characteristic wave number of 1 6
12、30 cm1. 4 Units The results of oxidation and nitration shall each be reported as absorption per centimetre of path length, A/cm. NOTE Absorption A is equivalent to the extinction as specified in DIN 51451. 5 Principle The infrared light is passed through a cell containing the sample to be analysed,
13、and the wavelength-dependent IR absorption measured at the respective wave numbers of the oxidation and nitration bands is compared with that of a sample of fresh oil. 6 Apparatus 6.1 Fourier Transform infrared spectrometer A standard commercial infrared spectrometer, preferably a Fourier Transform
14、infrared spectrometer (referred to as FT-IR spectrometer in the following text), meeting the requirements of DIN 51451 shall be used. NOTE Grating spectrometers are no longer used for determining the precision data in interlaboratory tests. 6.2 Cells Standard commercial liquid cells as in DIN 51451,
15、 having path lengths of 90 m to 120 m shall be used. In practice, KBr, NaCl and ZnSe have proved suitable as window materials. NOTE It should be noted that cells having KBr or NaCl windows can eventually be made unusable by water-containing oils and in such cases, regular checking of the path length
16、 is strongly recommended. 7 Sampling Samples shall be collected from the engine as generally specified in DIN EN ISO 3170 and in accordance with the particular measures in DIN 51574. DIN 51453:2004-10 4 The samples delivered to the laboratory shall be homogenized by agitation, by shaking, by rolling
17、 the bottle, by ultrasound or possibly by heating to not more than 60 C until two consecutive measurements are obtained that can be regarded as in visual agreement. Any heating necessary shall not alter the sample composition, for example as a result of the evaporation of fuel components. 8 Preparat
18、ion of FT-IR spectrometer The spectrometer shall be prepared as specified in DIN 51451 and the spectra shall be recorded with a resolution of 2 cm1. 9 Procedure Transfer an aliquot of the homogenized sample (see clause 7) to a cell (6.2) without trapping any bubbles. Record an IR absorption spectrum
19、 over a range of about 580 cm1to about 2 000 cm1. Repeat the same measurement with a sample of fresh oil of the same type in the same cell. The measurements may be recorded on paper and/or evaluated by a suitable computer program. 10 Evaluation of oxidation Determine the extent of oxidation by first
20、 subtracting the fresh oil spectrum from that of the used oil (see Figure 1) and then determining the absorbance at 1 710 cm1as specified in DIN 51451 with baseline endpoints of 1 970 cm1and 580 cm1. When reporting the result, convert the absorbance to a nominal cell path length of 1 cm. Key 1 Absor
21、bance 2 Wave numbers, cm1Figure 1 Difference spectrum for evaluating the oxidation absorption band DIN 51453:2004-10 5 11 Evaluation of nitration Determine the extent of nitration by first subtracting the fresh oil spectrum from that of the used oil (see Figure 2) and then determining the absorbance
22、 at exactly 1 630 cm1as specified in DIN 51451 with baseline endpoints of 1 645 cm1and 1 615 cm1. When reporting the result, convert the absorbance to a nominal cell path length of 1 cm. Key 1 Absorbance 2 Wave numbers, cm1Figure 2 Difference spectrum for evaluating the nitration absorption band 12
23、Expression of result Refer to this standard and report the oxidation and nitration values found as specified in clauses 10 and 11, respectively, to an accuracy of 0,1 A/cm. 13 Precision See DIN EN ISO 4259. 13.1 Repeatability limit (same operator, same apparatus) The absolute difference between two
24、successive results obtained under repeatability conditions will not exceed the numerical value given in Table 1 in more than 5 % of cases. DIN 51453:2004-10 6 13.2 Reproducibility limit (different operators, different equipment) The absolute difference between two individual results obtained under r
25、eproducibility conditions will not exceed the numerical value given in Table 1 in more than 5 % of cases. Table 1 Repeatability limit, r, and reproducibility limit, R a Repeatability limit, Reproducibility limit, r R For the oxidation, A/cm r = 0,049 X + 0,393 R = 0,059 X + 1,096 For the nitration, A/cm r = 0,048 X + 0,133 R = 0,245 X + 0,118 X is the mean of the results to be compared. aThe values obtained using the equations shall be rounded as specified in clause 12.
