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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Metrohm: Coulometric Karl Fischer Titration for ASTM D6304
Water in oils can occur in dissolved, emulsified and free states. 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.
Volumetric KF is most accurate in the range of ppm to percent water. 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. Once 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.
These include corrosion, erosion, etching and hydrogen embrittlement.
Analyzing Water in Oil
The two types of volumetric KF differ in the exact composition of titrant and solvent. F6304 Size and Reproducibility As with any analytical technique, the sampling error in KF analysis is inversely proportional to the sample size. However, alcohols cannot be completely removed from KF reagents, because the presence of alcohol is required by the mechanism of the KF reaction.
Chemistry asrm 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.
Coulometric KF Titration for ASTM D
With both types of volumetric KF, imidazole is the base used most frequently as a buffer to maintain optimal pH for the reaction. However, neither of these methods can detect dissolved water or reproducibly detect trace levels of emulsified water.
High water content of lubricating oils negatively impacts the operation and longevity of the oils and the mechanical equipment components being lubricated. 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 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.
Finding the Source of Water Contamination in Oil. Additionally, water has been known to cause certain oil additives to precipitate out, as well as to chemically attack some additives. Coulometric KF is considered an absolute method because time and current can both be accurately measured. Current Issue Archive Advertise. Machine Oil Case Study: Volumetric or 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.
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.
Toggle navigation Toggle search. The following reactions represent this two-step mechanism. Reactivity Certain compounds in the oil will undergo interfering side reactions either with methanol or iodine components of KF reagents.
However, due to solubility and reactivity issues described above, analysts often drastically reduce astn size, which tends to reduce the reproducibility of test results. Strategies for Removing Water from 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.
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. Distillation methods, such as ASTM D95 and D provide aastm 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.
A number of lubricating oil additives are reactive and are known to interfere with direct KF titration.
Analyzing Water in Oil
Create your own user feedback survey. KF analysis is a versatile and robust analytical tool for water content analysis in oil samples, and can detect water in any of three states commonly found in oils.
Medium-Sized Gear Machining Company. Corresponding reduction of hydride to hydrogen takes place at the cathode. Additionally, because the oil evaporator contains a miniaturized distillation set-up, only small sample 0. Coulometric KF is most accurate in the range of 1 ppm to 5 percent water.
Fundamentals of Volumetric Karl Fischer Titration. Modern Instrumental Methods and Techniques.