Every sampling operation is an experiment in probability. The effect on results using heterogeneous materials will be greatest when the granularity is divergent; the specific gravity differences are large; and the quality is widely ranged from the average. A Jones-type sampler is a practical compromise. Sampling is a process of crushing, mixing, and cutting; and the next steps are crushing, mixing and cutting-again and again to the final cut.
1. The sampler should be on a firm, level plane – all dimensions. All feed introduction should be at a level plane.
2. Test the sampler for equal splits. Adjust, bend, or shim the legs or frame for leveling.
3. Material should be mixed through the sampler at least once before making any cuts. Recombine by pouring individual splitsover each other or through the sampler again. After a split, mix it through the sampling device before making the next split.
4. Avoid a wide divergence of particle size. Coarse grains travel and change direction faster than fine grains. Large differences in particle size is the major cause of segregation and sample distortion.
5. Channels for material flow should be more than three times the maximum size particle. Greater widths are suggested especially for grains smaller than 10 mesh.
6. Material should be introduced to the cutters: a) at right angles, b) at a vertical or close to vertical drop , c) almost immediately after leav- ing the hopper or discharge container, d) at a speed consistent with the discharge capability of the sampler. Feed material should never be al- lowed to be hindered or pile up in a chute or cutter, e) equally (except moving, revolving chutes where constant and proper speeds are important, f) when feeding by hand, use the left as often as the right hand.