Applicazioni

The thermometric titration method presented here permits a simple and direct determination of the total acid number (TAN) in petroleum products. It is an invaluable alternative to current manual and potentiometric methods. Thermometric titration uses a maintenance-free temperature sensor that does not require rehydration and is free of fouling and matrix effects. The procedure requires minimal sample preparation. Results agree closely with those from the potentiometric titrimetric procedure according to ASTM D664, but the thermometric titration method is far superior in terms of reproducibility and speed of analysis, with determinations being complete in approximately one minute.

La determinazione del numero di acidità totale gioca un ruolo significativo nell'analisi dei prodotti petroliferi. Ciò risulta evidente dalle numerose procedure standard utilizzate in tutto il mondo (specifiche interne ad aziende multinazionali, specifiche nazionali e internazionali di ASTM, DIN, IP, ISO ecc). Tali procedure differiscono principalmente per la composizione di solventi e titolanti utilizzati.In questo bollettino si descrive il processo di determinazione del numero di acidità nei prodotti petroliferi mediante diversi tipi di titolazione.La determinazione potenziometrica è descritta ai sensi della norma ASTM D664, quella fotometrica ai sensi della norma ASTM D974, mentre la titolazione termometrica è descritta ai sensi della norma ASTM D8045.

Fully automated determination of the total acid number and total base number in engine oils according to ASTM D664 and ASTM D2896 is possible with the OMNIS Titrator.

The acid number (AN) is a measure for the quality of oils and their potential to enhance corrosion. When analyzing fresh, unused oils, the AN is used to ensure the specified quality from the manufacturer, whereas for used oils the AN is determined to observe its increase until a critical level is reached. Although it is generally assumed that the AN correlates to the corrosive potential of the oil, this is not exactly correct, as it is the change of the AN value which indicates this issue. Therefore it is necessary to determine the AN on a regular basis.Several standards already exist to determine AN via titration methods, however it is also possible to measure this parameter via spectroscopic (NIRS) methodology. No matter which technique you choose, Metrohm has you covered with high-performance instruments suitable for these published norms.