Mercaptan sulfur, test method

The mercaptan-sulfur determination may be waived at the option of the Inspector, if the fuel is considered Doctor sweet when tested in accordance with Method 5203 of Federal Test Method Standard No 791... 

Some sulfur compounds can also have a corroding action on the various metals of the engine system, varying according to the chemical type of sulfur compound present. Fuel corrosivity is assessed by its action on copper and is controlled by the copper strip test (ASTM D-130, IP 154), which specifies that not more than a slight stain shall be observed when the polished strip is immersed in fuel heated for 2 h in a bomb at lOO C (212°F). This particular method is not always capable of reflecting fuel corrosivity toward other fuel system metals. For example, service experience with corrosion of silver components in certain engine fuel systems led to the development of a silver corrosion test (IP 227). The mercaptan sulfur content (ASTM D-1219, ASTM D-3227, IP 104, IP 342) of jet fuels is limited because of objectionable odor, adverse effect on certain fuel system elastomers, and... 

Other test methods for the determination of corrosive sulfur (specifically hydrogen sulfide) are also available (ASTM D-6021, ASTM D-5705), which have been developed for residual fuel oil but can be applied to medicinal oil. Another test method (ASTM D-3227, IP 324) is used for the determination of mercaptan (R-SH) sulfur in petroleum products up to and including distillate fuels. However, there is no reason that the test could not be applied to mineral oil, with the use of any necessary modifications for solubility of the mineral oil in the alcoholic solution used for the titration. 

Doctor test n. Method for detecting the presence of mercaptan sulfur in gasolines, naphthas, and kerosenes. 

Hydrogen Sulfide and Mercaptan Sulfur in Liquid Hydrocarbons by Potentiometric Titration, Method 163, UOP Laboratory Test Methods for Petroleum and Its Products, UOP Inc., Des Plaines, IL, 1989. 

This test method covers the determination of mercaptan sulfur in gasolines, kerosines, aviation turbine fuels, and distillate fuels containing from 0.0003 to 0.01 mass % of mercaptan sulfur (Note 4). Organic sulfur compounds such as sulfides, disulfides, and thiophene do not interfere. Elemental sulfur in amounts less than O.OOOS mass % does not interfere. Hydrogen sulfide will interfere, if not removed as described in 9.2. 

This test method covers the determination of water in the range from 0.02 to 2 % in crude oils. Mercaptan and sulfide (S or H2S) sulfur are known to interfere with this test method (see Section S). 

The interference fiom mercaptan sulfur follows the theoretical stoichiometry of 1 to 0.28, that is 1000 pg/g (ppm) of mercaptan sulfur can generate a response equivalent to 280 pg/g (ppm) (0.03 mass %) water by this test method. The validity of correcting measured water contents for known mercaptan/sulfide sulfur levels has not been evaluated. 

D3227 Test Method for Mercaptan Sulfur in Gasoline, Kerosine, Aviation Turbine, and Distillate Fuels (Potentiometric Method) ... 

The test method does not purport to identify all individual sulfur components. Detector response to sul r is linear and essentially equimolar for all sulfur compounds within the scope (1.1) of this test method thus both unidentified and known individual compounds are determined. However, many sulfur compounds, for example, hydrogen sulfide and mercaptans, are reactive and their concentration in samples may change during sampling and analysis. Coincidently, the total sulfur content of samples is estimated from the sum of the individual compounds determined however, this test method is not the preferred method for determination of total sulfur. 

AMD 1 Particulate air filters for general ventilation - Requirements, testing, marking (AMD 8367) dated 15 November 1994. Superseded BS 6540 Part 1 1985 Natural gas - Determination of sulfur compounds. Determination of hydrogen sulfide, mercaptan sulfiir, and carbonyl sulfide sulfur by potentiometry. Also BS 3156 Subsection 11.4.3 1994 Natural gas - Determination of sulfur compounds. Lingener combustion method. Also BS 3156 Subsection 11.4.5 1994... 

Emissions. An environmental assessment has been carried out to evaluate the effects of sulfur-asphalt during and after construction. Ambient air samples were taken from points around the pugmill and paver and analyzed for hydrogen sulfide (H2S), sulfur dioxide (S02), carbon disulfide (CS2), carbonyl sulfide (COS), mercaptans (RSH), and total hydrocarbons. The results indicated that no problems exist in terms of current health standards during construction or after. Typical test results obtained at the pugmill and methods used are given in Table II. 

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