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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Since its invention by German petroleum chemist Dr. Medium-Sized Gear Machining Company. 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 satm the generator electrode, a component of the coulometric titration cell Figure 2.
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. Coulometric KF is most accurate in the range of 1 ppm to 5 percent water.
Additionally, water has been known to cause certain oil additives to precipitate adtm, as well as to chemically attack some additives. For those oil samples which fail to adequately dissolve even when using Asfm 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, as described below.
The end-point determination in KF titration occurs by means of bivoltametric indication. Axtm number of lubricating oil additives are aztm and are known to interfere with direct KF titration. Alternatively, specially preformulated KF reagents incorporating one or several of these solvents are commercially available for both volumetric and coulometric KF. However, due to solubility and reactivity issues described above, analysts often drastically reduce sample size, which tends to reduce the reproducibility of test results.
These include aldehydes, higher phenols, modified mercaptans, ketoacids, polysiloxanes, sulfides and metal oxides.
High water content of lubricating oils negatively impacts the operation and longevity of the oils and the mechanical equipment components being lubricated. The technique also offers other substantial advantages over more conventional hot plate crackle test and distillation methods, and it has been incorporated into numerous ASTM standards. 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.
Used oils may also contain 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.
Ast 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 reproducibility of KF analyses.
KF analysis is a versatile and robust analytical tool for water content analysis in oil samples, and astj detect water in any of three states commonly found in oils. Visual indication is asfm for quantifying water content only in the free state, while the hot plate crackle test can be used to detect free and emulsified water. These include corrosion, erosion, etching and hydrogen embrittlement.
Karl Asttm inKarl Fischer KF analysis has progressed from an esoteric laboratory procedure astmm a widely accepted instrumental method routinely used for water determination in the petrochemical industry.
Analyzing Water in Oil
Best Ways to Test for Water in Oil. Coulometric KF is considered an absolute method because time and current can both be accurately measured. Fundamentals of Volumetric Karl Fischer Titration. Understanding Oil’s Saturation Point.
However, alcohols cannot be completely removed from KF reagents, because the presence of alcohol is required by the mechanism of the KF asgm. 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.
Additionally, xstm the oil evaporator contains a miniaturized distillation set-up, only small sample 0. Sample Size and Reproducibility As with any analytical technique, the sampling error in KF analysis is inversely proportional to the sample size. Volumetric KF is most accurate in the range of ppm to percent water. The following reactions represent this two-step mechanism.
Toggle navigation Toggle search. Water in oils can occur in dissolved, emulsified and free states. Reactivity Certain compounds in zstm oil will undergo interfering side reactions either with methanol or iodine components of KF reagents.
Finding the Source of Water Contamination in Oil. Corresponding reduction of hydride to hydrogen takes place at the cathode.
Coulometric KF Titration for ASTM D
In two-component KF, the titrant contains only an alcoholic solution of iodine, while the solvent contains the other ingredients needed for the reaction. Machine Oil Case Study: Distillation methods, such as ASTM D95 and D provide better quantitative data in the range of approximately ppm to 25 percent, but require large sample sizes and involve long analysis times, typically 60 to minutes.
Furthermore, neither visual indication nor the hot plate test can be used to reliably quantify the water present. 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.
In other words, the larger the sample, the less error is introduced into the analysis by sample weighing, transfer and other handling.
However, neither of these methods can detect dissolved water or reproducibly detect trace levels of emulsified water.
Analyzing Water in Oil
Strategies for Removing Water from Oil. Modern Instrumental Methods and Techniques. It is estimated that nearlyKF determinations are performed daily around the world. In coulometry, the quantity of iodine generated corresponding to the amount of water present is calculated by the titrator on the basis of current aetm and time sec.
The two types of volumetric KF differ in the exact composition of titrant and solvent.
Oils have limited solubility d634 alcohols, such as methanol, which are typically used in common KF reagent formulations, while they are fully soluble in organic solvents like chloroform, toluene and xylene. Some of the modes by which water exists in lubricating oils can lead to catastrophic equipment failure. As a guideline, sample sizes shown in Table 1 are recommended for volumetric and coulometric KF, respectively.
In one-component KF, the titrant usually referred to as a CombiTitrant or a composite contains all the ingredients needed satm the KF reaction, namely iodine, sulfur dioxide, base and a suitable alcohol, while the solvent is typically dry methanol.
With both types of volumetric KF, imidazole is the base used most frequently as a buffer to maintain optimal pH for the reaction. Types of Titration Volumetric KF Volumetric Axtm proceeds in the conventional manner of a classic titration, in that the titrant containing iodine is added mechanically to the solvent containing the sample by the titrator’s burette Figure 1.