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 parameter of interest encompasses a large range. Sampling is an iterative process of crushing, mixing, and splitting.
To properly reduce a sample using a Jones type riffle splitter:
1. The splitter should be on a firm, level plane – all dimensions. All feed introduction should be at a level plane.
2. Test the unit for equal splits by weight sub samples to ensure they are within a few percent of each other. Adjust, bend, or shim the legs or frame to level if necessary.
3. Material should be mixed through the sampler at least once before making any cuts. Recombine by pouring individual splits over 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 chutes: a) at right angles, b) at a vertical or close to vertical drop , c) almost immediately after leaving the hopper or discharge container, d) at a speed consistent with the discharge capability of the sampler. e) Feed material should never be allowed to be hindered or pile up in a chute or cutter, f) when feeding by hand, use the left as often as the right hand.