TABLE OF CONTENTS To get a correct sample, we must define the sample using the correct geometry for the sampling dimension we have produced or been given. We must then use a tool that will extract the sample we have defined. As we have seen, practical situations are not nearly as easy as sampling blocks. Consequently, we may not be able to reduce the sampling dimension. Even if we do, we still may compromise the principle of correct sampling. In this section we examine several sampling situations and the tools that might be used. Both advantages and shortcomings will be discussed.
A common tool used to sample bulk solids is a thief probe, shown earlier in Figure 3.6. When the sampling dimension is two, a thief can be used to sample across the third dimension. It is often employed for sampling a vertical core from large bags or drums. For taking a horizontal cross section from a small bag, the point is used to punch through the outside packaging and push through the material. A knob at one end is used to open and close a set of windows along the length of the cylindrical shaft. The pointed end allows penetration of the material. To use the thief, the windows are closed and the thief is pushed through the material. The windows are opened to allow material to flow in and then closed before pulling out the thief. For loosely packed solids, this tool works fairly well.
