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Neutralisation or Acid Number

Neutralisation number

  
OELCHECK test instrument: Metrohm photometer 662 to determine NN
Sample quantity: 13 ml for NN
Unit: mgKOH/g
Test result:NN (neutralisation number)
Result range: 0.01 - 99 mg KOH/g
Analysis for: all industry oils e.g. from gears, hydraulics, heat transfer systems, transformer oils, oil circulation systems, landfill gas engines
Brief description: The neutralisation number (NN) indicates the amount of potassium hydroxide required to neutralise the acids contained in a gram of oil. At the NN, an indicator is added to a mixture of oil and solvent which will indicate the neutral state during titration through a colour change.
Statement: By comparison with the values of the fresh oil, the Neutralisation Number allows conclusions to be drawn regarding the oxidation of the oil and the breakdown of oil additives. It provides essential supplementary information for the extension of oil change intervals. 
Underlying test standard: DIN ISO 6618, ASTM D974
Comparable methods: ASTM D664: potentiometric determination of the acid number
ASTM D8045: AN determined for petroleum and petroleum products using a thermometer

Acid Number

OELCHECK test instrument: Mettler Toledo Excellence titrator 90, Mettler Toledo DL 67
Sample quantity: 5 ml for AN
Unit: mgKOH/g
Test result: AN (Acid Number), SAN (Strong Acid Number)
Result range: 0.01 - 99 mg KOH/g
Analysis for: all industry oils e.g. from gears, hydraulics, oil circulation systems, transformer oils, heat transfer systems, landfill gas engines
Brief description: The Acid Number (AN indicates) the amount of potassium hydroxide required to neutralise the acids contained in a gram of oil. If the sample is too dark to determine the neutralisation number at which an indicator, when added to a mixture of oil and solvent, will indicate the neutral state through a colour change, the AN shall be determined for these samples. In that instance, a titrant (KOH) is added to the mixture of oil and solvent until the mixture is "neutral". This is detected using a potentiometer and is shown by an inflection point in the titration curve. Using titrant up to this inflection point indicates the AN.
Statement: By comparison with the values of the fresh oil, the Acid Number allows conclusions to be drawn regarding the oxidation of the oil and the breakdown of oil additives. It provides essential supplementary information for the extension of oil change intervals. The SAN (Strong Acid Number), unit mgKOH/g, is only recorded in AN titration when the oil contains strong, aggressive acids, such as those used in gas engines with landfill gas.
Underlying test standard: ASTM D664
Alternative methods: DIN EN 12634: another solvent and titrant used and SAN not recorded
Comparable methods:DIN ISO 6618: neutralisation number determined using a photometer
ASTM D8045: AN determined for crude oil and crude oil products using a thermometer