Sampling methods are designed to capture a sample of the material in a tank; or flowing through a pipeline that is representative of the whole. There are many conditions which may cause a sample to be nonrepresentative; such as stratification resulting from temperature, density or other differences in product composition. If these differences are extreme, it may be impossible to obtain a representative sample by manual methods.
Caps, Restricted Flow Caps, Split Corks, or Stoppers Sampling equipment must be properly maintained to obtain good samples. Sampling equipment must first be clean. Some analytical tests measure impurities to ppm (parts per million) and even ppb (parts per billion). Therefore, a very small amount of residue in a sample container can result in an erroneous test result. This is the principal drawback of the beaker sampler. It is difficult to ensure that all residue from the previous sample is removed. In addition, sample cords must not contain residue from incompatible material.
2.1 Introduction The Sampling is one of the most important job functions performed. The concept of sampling is to take a small portion of a product that is representative of a much larger portion. Usually, the amount of sample taken is only a tiny fraction of a percentage of the entire cargo. Therefore, the importance of exercising due care and diligence when taking samples cannot be over emphasized. Laboratories typically have millions of dollars invested in equipment, some of which can measure down to parts per billion. However, all this investment in equipment is only as good as the sample that is taken. All the laboratory equipment in the world cannot compensate for a nonrepresentative sample. Samples of crude oil and petroleum products are taken to determine physical properties (such as API and S&W, chemical components, such as sulfur and benzene), and compliance with quality specifications such as those required in sales contracts. Samples may also be taken to ensure that the commodity is not contaminated during transfer. Sampling technique is important because oil and chemical products may not be homogeneous and may contain impurities.
2.2 Equipment A variety of equipment is used to perform
manual sampling, some of which are shown in the figure on the following page. These include: Natural Fiber Cord or Chain Amber, Clear Glass, Plastic Bottles or Metal Cans (Sometimes Lined) Sample Thief’s, Beakers, Sampling Cans, Bacon Bombs or Zone Samplers Lead Weight or Bottle Catcher (Cage)
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