1.1 This standard is applicable to the determination of the amount of constituents in petroleum products (such as lubricants, additives, and transmission fluids) that will saponify under the conditions of the test.
Two test methods are described in this standard: Method A- Color Indicator Titration (Chapters 6-11), and Method B- Potentiometric Titration (Chapters 12-19).
1.2 Because compounds of sulfur, phosphorus, the halogens, and certain other elements that are sometimes added to petroleum products also consume alkali and acids, the results obtained indicate the effect of these extraneous materials in addition to the saponifiable material present. Results on products containing such materials, on used internal-combustion-engine crank-case oils, and on used turbine oils must be interpreted with caution.
Note 1: The materials referred to above, which are not normally considered saponifiable matter, include inorganic or certain organic acids, most non-alkali soaps, and so forth. The presence of such materials increases the saponification number above that of fatty saponifiable materials for which the test method is primarily intended. The odor of hydrogen sulfide near the end of the back-titration in the saponification test is an indication that certain types of reactive sulfur compounds are present in the sample. In the case of other reactive sulfur, chlorine, and phosphorus compounds and other interfering materials, no simple indication is given during the test. A gravimetric determination of the actual amount of fatty acids is probably the most reliable method for such compounds.
1.3 This standard only provides some explanations for particular danger related with the test process and does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
2 Normative References
The following documents contain provisions which, through reference in this standard, become provisions of this standard. For dated reference, subsequent amendments (excluding amending error in the text) to, or revisions of, any of these publications does not apply. However, the parties whose enter into agreement according to this standard are encouraged to research whether the latest editions of these references apply or not. For any undated references, the latest edition of the normative document referred to applies.
GB/T 4756 Petroleum Liquids-Manual Sampling (GB/T 4756-1998, egv ISO 3170: 1988)
GB/T 6682 Water for Analytical Laboratory Use - Specification and Test Methods (GB/T 6682-1992, neq ISO 3696: 1987)
SH 0005 Stoddard Solvent for Paint Industry
3 Terms and Definitions
For the purpose of this standard, the following terms and definitions apply.
3.1 Saponify
To hydrolyze a fat with alkali to form an alcohol and the salt of a fatty acid.
3.2 Saponification number
The number of milligrams of potassium hydroxide consumed by 1g of a sample under the conditions of the test.
Note: The value of the saponification number in these test methods can be affected by the presence of other alkali-reactive species, as described in the note in 1.2.
4 Summary of Test Methods
4.1 A known mass of the sample is dissolved in a suitable solvent, such as butanone (methylethylketone), xylenes, or Stoddard Solvent, or a combination thereof, and is heated with a known amount of alcoholic potassium hydroxide (KOH). The excess alkali is titrated with standard acid, and the saponification number is calculated.
4.2 The titration end point can be detected either colorimetrically (Method A) or potentiometrically (Method B).
