Buy ASTM D TEST METHOD FOR DETERMINATION OF WATER IN PETROLEUM PRODUCTS, LUBRICATING OILS, AND ADDITIVES BY. Distillation methods, such as ASTM D95 and D provide better . This innovative KF technique is incorporated in ASTM D (Method B) and is applicable. If a crackle test is positive, further testing is needed to quantify the amount of water by using The Karl Fischer Water titration by ASTM D A measured.

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Analyzing Water in Oil

However, neither of these methods can detect dissolved water or reproducibly detect trace levels of emulsified water. In coulometry, the quantity of iodine generated corresponding to the amount of water present is calculated by the titrator on the basis of current mA and time sec. In d304 KF, the titrant usually referred to as a CombiTitrant or a composite contains all the ingredients needed ashm the KF reaction, namely iodine, sulfur dioxide, base and a suitable alcohol, while the solvent is typically dry methanol.

The procedure involves adding the oil sample to the solvent present in the evaporation chamber where it dissolves in the solvent, and in the process forms a binary azeotrope between the solvent and the sample’s water content.

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Understanding Oil’s Saturation Point. For those oil samples which fail to adequately dissolve even when using KF reagents formulated with organic co-solvents, or those that are suspected of containing interfering compounds, an indirect KF analysis using an oil evaporator is recommended, astj described below. These include aldehydes, higher phenols, modified mercaptans, ketoacids, polysiloxanes, sulfides and metal oxides.

Coulometric KF Titration for ASTM D

In other words, the larger the sample, the less error is introduced into the analysis by sample weighing, transfer and other handling. That d66304, while the iodine in the KF reagent is reacting with water, there is no free iodine present in the titration cell, and a high voltage is required to maintain the set polarization current at the double platinum pin indicator electrode.


Since its invention by German petroleum chemist Dr. Modern Instrumental Methods and Techniques. However, due to asgm and reactivity issues described above, analysts often drastically reduce sample size, which tends to reduce the reproducibility of test results.

Metrohm: Coulometric Karl Fischer Titration for ASTM D6304

As a guideline, sample sizes shown in Table 1 are recommended for volumetric and coulometric KF, respectively.

Techniques for Successful KF of Oil Samples Direct Titration Sample solubility issues may be overcome by using co-solvents such as chloroform, toluene or xylene to increase the solvent capacity of conventional KF reagents in the titration cell. Fundamentals of Volumetric Karl Aetm Titration. These include corrosion, erosion, etching and hydrogen embrittlement.

Finding the Source of Water Contamination in Oil. Recommended Sample Sizes for KF Analysis Sample Size Selection For both direct and indirect KF methods, sample size selection is critical for minimizing errors associated with sample weighing, transfer and injection. The following reactions represent this two-step mechanism. The subsequent oxidation of the alkylsulfite salt to an alkylsulfate salt by iodine consumes water in a 1: It is estimated that nearlyKF determinations astmm performed daily around the world.

Key Components of a Modern Volumetric KF Titrator Coulometric KF In coulometric KF, the iodine needed by the KF reaction is not present in the KF reagent, but is instead generated electrochemically in situ from iodide at the anode of the generator electrode, a component of the coulometric titration cell Figure 2.

Sample Size and Reproducibility As with astj analytical technique, the sampling error in KF analysis is inversely proportional to the sample size.

Additionally, water has been known to cause certain oil additives to precipitate out, as well as to chemically attack some additives. Create your own user feedback survey. Some of the modes by which water exists in lubricating oils can lead to catastrophic awtm failure. Water in oils can occur in dissolved, emulsified and free states.

Analyzing Water in Oil

With both types of volumetric KF, imidazole is the base used most frequently as a buffer to maintain optimal pH for the reaction. Additionally, because the oil evaporator contains a miniaturized distillation set-up, d3604 small sample 0. Reactivity Certain compounds in the oil will undergo interfering side reactions either with methanol or iodine components of KF reagents.


Best Ways to Test for Water in Oil. The two types of volumetric KF differ in the exact composition of titrant and solvent. The KF method does not suffer from the same issues and limitations associated with the other techniques described above, and a number of recent advances in titrator instrumentation and reagent formulations have further improved the accuracy and d3604 of KF analyses. However, alcohols cannot be completely removed from KF reagents, because the presence of alcohol is required by the mechanism of the KF reaction.

The technique also offers other substantial advantages over more conventional hot plate crackle test and distillation methods, and sstm has been incorporated into numerous ASTM standards. The distillation component of the indirect titration method ensures that the hard-to-dissolve oil samples, or those containing potentially interfering compounds, are not introduced to the titration cell, while the KF titration component of the method accurately quantifies the water content of the azeotropic vapor carried into the titration cell by the dry gas.

Visual indication is reliable for quantifying water content only in the free state, while the hot plate crackle test can be used to detect free and emulsified water. KF analysis is a versatile and robust analytical tool asm water content analysis in oil samples, and d604 detect water in any astj three states commonly found in oils. Chemistry and Principles Karl Fischer titration proceeds according to a reaction with a two-step mechanism in which sulfur dioxide initially reacts with an alcohol ROH to form an ester intermediate which is neutralized, or buffered, by an appropriate organic base RN.

Used oils may also aatm contaminants that can potentially interfere with direct KF analysis, such as trace metals, polyaromatic hydrocarbons, polychlorinated biphenyls, as well as various products of incomplete combustion.