GR Scientific have launched a new micro system for Total Acid Number (TAN) analysis of oil samples. A micro combination pH electrode and optimised titration vessel have been developed specifically to address the reduction in organic solvent consumption. The system enables the user to save up to 75% of the volume and cost of organic solvent used in the analysis. The new system reduces the cost per test to around £1 and greatly reduces the cost of waste solvent disposal. The reduction in the use of organic solvents not only offers the user a saving in the cost of running the analytical system but has significant health and safety benefits. It is an easy to use system and developed specifically for the wide range of TAN values expected from Oil industry samples.
The standard test method for measuring the Total Acid Number of petroleum products by potentiometric titration is ASTM D664. Today, automatic titration systems are used to carry out the analysis. Total acid number is calculated from the titration volume of alcoholic potassium hydroxide solution reaching the endpoint. Petroleum products and lubricants dissolved in the mixed solvent contain such components as organic acids, inorganic acids, esters, phenolic compounds, lactone, resins, heavy metal salts, ammonium salts, weak acids and polybasic acid chloride.
Operators of equipment use fluids including engine oil, hydraulic oil, gear oil, transmission oil and grease. These products are vital to the performance and lifetime of the equipment. The oils are there to protect and lubricate, reduce friction, clean vital parts, maintain compression, lubricate seals and to operate under pressure. Detailed analysis of a sample of engine, transmission and hydraulic oils is a valuable preventive maintenance tool. The analysis can contribute to:
- reduced service and operating costs.
- highlight problems and maintenance requirements.
- maintain productivity and limit downtime.
- higher resale values.
In many cases it enables identification of potential problems before a major repair is necessary, reduce the frequencies of oil changes and the overall cost of ownership.
Oils continually react with atmospheric oxygen to produce organic oxidation products that are acidic in nature. At ambient temperature, this reaction is very slow and has little effect upon oil conditions. At the elevated temperatures that exist within an operating engine, reaction rates are much higher. Elevated operating temperatures can generate high levels of weak organic acids. They cause increased oil viscosity and can deposit as lacquers on hot surfaces.
Total Acid Number or TAN is the measure of both the weak organic and strong inorganic acids present in oil. It is applicable to gearbox, gas engine, gas turbine and hydraulic lubricants. It is an important quality measurement of crude oil. The TAN value indicates to the crude oil refinery the potential of corrosion problems. Total Acid Number is an analytical test to determine the deterioration of lubricants. The more acidic a lubricant is, the further its degradation has proceeded. Theoretically, the Total Acid Number (TAN) is the amount of potassium hydroxide in milligrams that is needed to neutralize the acids in one gram of oil. TAN values can be measured by potentiometric titration. The sample is dissolved in toluene and propanol with a little water and titrated with alcoholic 0.1M potassium hydroxide. A pH glass microelectrode is immersed in the sample and connected to the instrument. The meter reading (in millivolts) is plotted against the volume of titrant. The end point is taken at the distinct inflection of the resulting titration curve corresponding to the basic pH 11 buffer solution.
http://www.grscientific.com/micro-tan-titrator/
