Linings, combustible, test methods

Test methods that might be used for sulfur determination applications in fuels include techniques such as lead acetate paper tape, oxidative combustion followed by gas chromatographic separation for flame photometric detection [4], and energy dispersive X-ray fluorescence with coaxial proportional counter detectors [5]. The first of these two methods was recently issued as a new standard D 7041 by ASTM. However, these and other corrunercially available analyzers, such conventional on-line/at process sulfur by combustion and UVF analyzers typically require analytical cycle times of 4—10 min. This delay in reporting the sulfur concentration levels limits the real time detection capability of changes in the sulfur concentration of fast moving or rapidly changing transport or process streams. 

Significant advances in sample introduction, combustion technique, and the handling of combustion byproducts have been incorporated into the basic on-line Sulfur by UV Fluorescence analyzer. The implementation of these new techniques has yielded a continuous rapid sulfur measurement capability that is based upon the reliable and well-established D 5453 standard test method. Figure 4 describes a typical high speed sulfur analyzer. 

In a third on-line application paper for sulfur analysis, Rhodes (Rhodes Consulting), ASTM Test Method D 6920 is applied for on-line application. This method uses pyro-combustion followed by electrochemical detection. 

In this case, an intercalibration study served not only to test the ability of the various laboratories to perform an analysis, it also pointed out the steps in the determination which required further research. The high temperature catalytic oxidation (HTCO) technique has become much more common in this field, with several companies now supplying suitable instrumentation. This technique is not only simpler to run than the older wet oxidation methods, it also allows almost-real-time analyses at sea. The problem of the production of a proper blank, and therefore of a proper reference material for the DOC analysis, has yet to be solved at this time it is being patched by the use of low DOC deep water as a blank, or of water which has passed through the combustion chamber of the analyzer and subsequently condensed. Placing DOC and total nitrogen (TN) detectors in-line has made simultaneous determinations of both quantities on the same sample a routine procedure [53]. 

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