Chute splitting

The rotary sample divider or spinning riffler was first described in 1934 [20] and conforms to the golden rules of sampling. The preferred method of using this deviee is to fill a mass flow hopper in such a way that segregation does not occur. The table is then set in motion and the hopper outlet opened so that the powder falls into the collecting boxes. The use of a vibratory feeder is recommended to provide a constant flowrate 

The mixtures in these experiments contained particles all the same size hence the main cause of segregation was not present and the conclusions may not apply in the more usual case where segregation occurs. Several commercial versions of this instrument are available, some of which were designed for free-flowing powders, some for dusty powders and some for cohesive powders. They handle quantities from 40 liters down to a few grams. 

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Chute splitter Subsampler A series of chutes split sample repeatedly Large Can be repeated until the desired sample size is achieved If segregation occurs, the result can be misleading Prone to operator bias... 

A tool used to split a sample in half by pouring the lot into chutes emptying into two containers. 

This apparatus is a V-shaped trough, at the bottom of which is a series of chutes feeding two trays on either side of the trough. The sample enters the chute and is halved repeatedly until the desired sample size is achieved. The distance between the slots should be at least three times the size of the largest particle diam-eter.f This method is prone to segregation and operator bias because of the unequal splitting of the sample. It has been found that a greater number of chutes can increase the overall efficiency. 

Whenever a process stream is divided (e.g., a bifurcated chute to feed two sides of a press), a symmetrical split should be maintained to eliminate potential differences in the flow between the two streams (61). Consideration must be given to any potential for segregation upstream of the split. Even little details like orientation of a butterfly valve prior to a split can affect segregation. Proper designs should be utilized for hopper, Y-branches (Fig. 12) to avoid stagnant material and air counter flow. 

A subdivision of the remaining batch of about 25 kg was achieved in two stages. A chute riffler was used to split the batch in eight portions. Each of these portions was then passed through a spinning riffle which further subdivided the material in 2500 samples of ca. 10 g. Each sample was put into a brown glass bottle with a plastic screw stopper. 

Feeding the machine is then in two parts - one position for the ignition layer and one for the main layer. In some machines entirely separate feed systems are used in others the feed is split to the ignition hopper and the main hopper using an intermittent diversion chute or conveyor. The disadvantage of the latter system is that the level in the hoppers varies and as indicated above can vary the packing density of the sinter charge. It also makes smooth control of the machine more difficult if controls are linked to the level of material in the main feed hopper. 

Unlike the chute which must be set at a relatively large declined angle to ensure that the bulk will slide against the chute surface, most vibratory conveyors are used for horizontal or near horizontal conveying with the exception of vibratory elevators which will be discussed later. They can convey on moderate (about 15°) upward and downward slopes. It is possible to design in multiple inlets and outlets to the conveyor. The outlets can either be a series of gates in the trough, or otherwise the stream can be split in some way to provide a number of... 

The discard having been sheared off, the dummy is knocked out of the shell and placed upright on a small platform (see Fig. 67), from where it is lifted by actuating a hand-lever, whereupon it rolls off through an inclined chute / on to a rotary table z and after a 90" turn through the chute y right in front of the container. The rotary table is moved by actuating a foot pedal. This chute y is split to allow for the container to be shifted. 

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