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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The two types of volumetric KF differ in the exact asmt of titrant and solvent. The subsequent oxidation of the alkylsulfite salt to an alkylsulfate salt by iodine consumes water in a 1: Fundamentals of Volumetric Karl Fischer Titration.
Coulometric KF is most accurate in the range of 1 ppm to 5 percent water. Machine Oil Case Study: Coulometric KF is considered an absolute method because time and current can both be accurately measured. These include corrosion, erosion, etching and hydrogen embrittlement.
Understanding Oil’s E6304 Point.
Coulometric KF Titration for ASTM D
Best Ways to Test for Water in Oil. X6304 the Source of Water Contamination in Oil. 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. Since its invention by German petroleum chemist Dr.
Zstm all the water has reacted with the iodine, trace quantities of free iodine appear in the titration cell, causing a drop in voltage necessary to keep the polarization current constant, which in turn signals the end-point of the titration.
KF analysis is a aetm and robust analytical tool for water content analysis in oil samples, and can detect water in any of three states commonly found in oils. A number of lubricating oil additives are reactive and are known to interfere with direct KF titration.
Analyzing Water in Oil
In coulometry, the quantity of iodine generated corresponding asttm the amount of water present is calculated by the titrator on the basis of current mA and time sec. 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.
Additionally, because the oil evaporator contains a miniaturized distillation set-up, only small sample 0. Volumetric astj coulometric KF methods, utilizing either direct titration or the oil evaporator technique, can be used to quantify water in oil samples from trace amounts to percent. Types of Titration Volumetric KF Volumetric KF 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.
It is estimated that nearlyKF determinations are performed daily around the world. In other words, the larger the sample, the less error is introduced into the analysis by sample weighing, transfer and other handling. Reactivity Certain compounds in the oil will undergo interfering side reactions either with methanol or iodine components of KF reagents.
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. In two-component KF, the titrant contains only an alcoholic solution of iodine, while the solvent contains the other ingredients needed for d604 reaction.
Oils have limited solubility in 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. Additionally, water has been known to cause certain oil additives to precipitate out, as well as to chemically attack some additives. However, alcohols cannot be completely removed from KF reagents, because the presence of alcohol is required by the mechanism of the KF reaction.
Create your own user feedback survey. Current Issue Archive Advertise. 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 d634 products of incomplete combustion.
Ast, both types of volumetric KF, imidazole is the base used most frequently as a buffer to maintain optimal pH for the reaction. Medium-Sized Gear Machining Company. Toggle navigation Toggle search. Strategies for Removing Water from Oil. Water in oils can occur in dissolved, emulsified and free states.
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.
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 ashm solvent and the sample’s water content. 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.
In one-component KF, the titrant usually referred to as a CombiTitrant or a composite contains all the ingredients needed for the KF reaction, namely iodine, sulfur dioxide, base and a suitable alcohol, while the solvent is typically dry methanol.
Metrohm: Coulometric Karl Fischer Titration for ASTM D6304
Alternatively, specially preformulated KF reagents incorporating one or several of these solvents are commercially available for both volumetric and coulometric KF. The distillation component of the indirect titration method ensures axtm the hard-to-dissolve oil samples, or those containing potentially interfering compounds, are not introduced to the titration cell, while sstm KF titration component of the method accurately quantifies the water content of the azeotropic vapor carried into the titration cell by the dry gas.
Volumetric KF is most accurate in the range of ppm to percent water. As a guideline, sample sizes shown in Table 1 are recommended for volumetric and coulometric KF, respectively. Sample Size and Reproducibility As with any analytical technique, the sampling error in KF analysis is inversely proportional to the sample size. These include aldehydes, higher phenols, modified mercaptans, ketoacids, polysiloxanes, sulfides and metal oxides.
Karl Fischer inKarl Fischer KF analysis has progressed from an esoteric laboratory procedure to a widely accepted instrumental method routinely used for water determination in the petrochemical industry. Corresponding reduction of hydride to hydrogen takes place at the cathode. Modern Instrumental Methods and Techniques. That is, while the iodine in the KF reagent is reacting with water, there is no dd6304 iodine present in the titration cell, and a high voltage is adtm to maintain the set polarization current at the double platinum pin indicator electrode.