Batch weight

The principle of operation of batch-type scales is based on the concept that a flowing stream of material has constant density. If this is true, then if at some point in advance of the desired batch weight the stream is cut off, the amount of material flowing will remain con-... 

Transfer of solids in sealed containers or plastic sacks in preset batch weights, so avoiding emptying for reweighing. 

Illustration of product differential pressure with Increasing batch weight... 

On the production scale, pan loading often has nothing to do with the ideal loading for the pan, but rather with the total batch weight of the compressed tablets, and how evenly these can be divided into a whole number of pan loads. For example, if the total batch weight is 500 kg, and these tablets are to be coated in a pan that optimally holds 120 kg per run, then the instructions will call for five pan loads of 100 kg each to be coated. The result is that each coating run will have each pan underloaded by about 16%. 

Thus, during product and process development, even though compression batch weights are often defined in terms of the capacities of blenders, granulators, dryers, etc., there is sufficient justification, when the product is to be coated, to keep in mind the capacities of the coating pans that will be used. 

Limited batch weight flexibility Limited weight gains... 

Top spray Larger batches Limited batch weight Application of ... 

Although these examples are more specific to the Wurster process, similar guidelines can be applied to the top-spray process, in which case the definition for working capacity will be different. When dealing with the tangential-spray process, the quantity of product that is sufficient to ensure that the spray nozzles are completely immersed when the product is in motion will define the minimum starting batch weight. 

Scales currently used are usually based on load cells. Modem weight indi-cators/controllers have outputs that can be connected to valves that control the flow of the material. Batch weights can also be stored in some units. 

Candy base is prepared from liquid sugar (67% sugar) and corn syrup (liquid glucose 43°Be, 80% solids) in a ratio of about 60 40. Precooking is initiated under vacuum at controlled temperature. The precooked solution is transferred into the steam-heated coil, where it is boiled and from which it is moved to the intermediate chamber where final mixture is produced. The final moisture content of candy base should be about Wo, its temperature about 135°C, and its consistency plastic-like. The candy base is transferred into a kettle mounted on a suitable scale and, if necessary, batch weight is adjusted. 

Compounds may also be mixed on open mills, but this takes considerably more time, batch weights are lower, and it is thus less efficient than use of internal mixers. 

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