Sampling Services
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The value of a coal cargo is determined by testing a sample collected manually or by a mechanical coal sampling system. If the sampling method or the sample preparation is biased or inconsistent, the value of the cargo can be inaccurately or imprecisely determined. This results in the cargo being over or under-valued, and the buyer or seller is then erroneously compensated for the value of the cargo. Expensive, wrong decisions can be made based upon biased, incorrect, or erratic data. SGS will work closely with your staff to insure the highest practical work with the minimum practical interference with your operations. SGS provides the accurate technical expertise to allow you to know the exact quality of coal that you have. SGS focuses on three specific types of sample testing, which includes: Coal is one of the most difficult materials to sample because it is a highly heterogeneous with respect to its inorganic and organic constituents. Coal is widely variable with respect to size and chemical composition and it can be completely combustible, completely noncombustible or in any combination between. The process for determining the quality and Gross Calorific Value (GCV) of coal begins with sampling, a process that is not as easy as it may appear. A sample is collected to estimate the quality of a lot of coal. There are uncertainties associated with the estimate and how it relates to the true value. Statistics provide a means to calculate this uncertainty. If the uncertainty is known, the risk of using a sample to represent the lot is reduced. SGS has years of experience in sampling and is a leader in the field of bulk material dynamic sampling theory. When sampling coal, it is important that every particle of coal in the lot has an equal opportunity of being collected. If this is not the case, the sample is not representative. The minimum mass of the gross sample should be sufficient to ensure that coal particles appear in the sample in the same proportions as in the entire lot it was taken from. In a proper sampling system, the results from a group of samples would fall into a normal distribution curve. The most probable results would lie in the center of curve, while less likely results would lie to either side. To reduce the sampling uncertainty, make the width of the normal distribution curve as small as possible, requires excellent design and execution of a sampling plan. |
