01 December 2007
Andy Quail

Many buyers of dust and fume extraction equipment only consult the manufacturer after the machinery it will operate on has already been installed. Consulting the experts at this late stage can lead to reduced performance, inefficient extraction and increased costs.

By bringing in dust extraction professionals at an early stage, buyers can make big savings and acquire a highly efficient, custom-designed dust extraction system. Such action also minimises the need for personal protective equipment (PPE).

Designing out dust

Dust extraction is often seen as an expensive addition to important production equipment. With no overt financial return, it can become an unnecessary irritant between management and employees, thought to cause loss of production and take up vital resources.

But with increasingly stringent legal requirements for health and safety, dust and fume extraction equipment is no longer a bolt-on extra. It is essential to consider the risk of dust generation at an early stage when designing machinery or purchasing process equipment. This can reduce plant costs and improve working conditions, product quality and presentation.

When designing processes or machinery, first consider the risks of generating dust or fumes when handling a material. Careful selection of the material or its treatment is an essential first step in reducing the generation of dust or fumes. Next make a thorough analysis of the proposed operations and their sequence. This analysis should aim to reduce the generation of dust particles or to produce larger particles.

Suppression and enclosure

Unfortunately it is difficult to eliminate dust generation completely. However, there are a number of options for reducing and collecting the dust generated, including suppression, total enclosure or partial enclosure. The choice of approach will depend on the process being planned.

Dust suppression will depend on the type of work being carried out and the effect of the suppressant on the dust and its application. Consider this type of solution in light of the end use of the products and the effect of any liquid used in the process. Take care not to introduce additional hazards associated with fine mists and uncontrolled liquors.

Total enclosure is often impractical and dust trapped in the enclosure will need to be removed before maintenance can be carried out. There is also the risk of explosion, damage and wear on bearing surfaces, plus the risk of product contamination. It is difficult to seal an enclosure - some means of overcoming the pressure build-up within the arrangement must be found. This may be achieved by inducing a small negative pressure generated by a dust collector. However, this can lead to high concentrations of dust within the product.

The most common approach is the partial enclosure - either receptor or capture hood. The receptor hood is designed to receive the dust particles as they are generated. This is a cost-effective system requiring much less air and therefore smaller dust collection plant. A capture hood needs more air to draw the dust into the system and as a consequence larger extraction equipment.

Plant and equipment

It is essential to ensure that the filter size and efficiency are compatible with the hooding design and operation or the system will not function efficiently.

No amount of sophistication in filter material or unit design will give an optimum solution unless you consider the specific application, plus the type and design of the hooding.

It is also vitally important to understand all aspects of the operation that is generating the dust, including the type of dust. Proper application of the dust extraction unit should then eliminate unnecessary costs and customer disappointment because of a shortfall in performance.

Once a system is installed, regular service and maintenance is essential to sustain design performance. If there are any changes in the dust-generating operations, you also need to reconsider the dust control system balance and the resulting effects on the extraction equipment.

Simply adding connections to an existing system can wipe out the efficiency of a previously well-balanced system. If additions or changes are planned, the system should be reassessed and if necessary re-designed by experienced engineers.

Added value

Correctly-designed dust extraction equipment will help companies meet their legal and moral obligations towards their employees, protecting them from current or future hazards. Secondary hazards, such as the removal and disposal of the collected dust, are an equally important consideration, as they can cause great difficulties unless the dust is controlled in some way.

Any added value to the product will depend on the requirements of the customers and the industry sector, but the food and pharmaceutical industries are just 2 examples of sectors where it is a big advantage to be able to sell a "dust-free" product.  Extraneous dust present during manufacture may discolour the product, collect on the corners of packages and cloud the packing, reducing product appeal. With the right dust extraction system these problems can be overcome and product quality improved.

It therefore makes good sense to involve experienced dust and fume extraction engineers in the early design stages. This way you can reduce costs, add value to the product and protect staff and the environment.

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