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Cyclone Screener for APIs Screening API Without Exposure: How to Ensure Containment in Screening and Maintenance

| Author / Editor: Frank Pahl* / Manja Wühr

New containment cyclone screener — Screening products under containment conditions is one matter. Maintaining and inspecting cyclone screeners without exposure is another. Now Azo has designed a new real containment solution that utilise a flexible film liner technology.

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Inspecting the screen cylinder using the maintenance hatch
Inspecting the screen cylinder using the maintenance hatch
(Pictures: Azo )

Containment has been a core issue for years in the pharmaceuticals industry particularly. Low occupational exposure limits and complex toxicological evaluations pose special challenges for processors and manufacturers of highly active substances with regard to process safety. On top of this, there are new regulations, such as the modified EU GMP directives, which came into force on 1 March 2015.

Thanks to engineering design solutions, today’s plants now generate so little dust in regular operations that it is possible to rule out any threat to the health of plant operating staff from harmful dust. The situation is far more critical when maintenance or cleaning work has to be carried out.

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Inspection hatches have to be opened in order to inspect working parts in machinery and plants. In the case of maintenance activities, maintenance staff have to remove worn components and install new replacement parts. In the past, this was only possible within isolators when smaller plants and machines were concerned or, when larger machines were concerned, by wearing full body protection. Installation in an isolator is not possible in the case of cyclone screeners for reasons of handling and space, which is why Azo has developed the type DA … Vario Containment screener.

Containment cyclone screener

With its newly designed DA … Vario Containment screener, Azo provides an entirely new solution to satisfy the above-mentioned requirements: Based on the DA screener, tried and tested in actual practice for years, and on the widespread practice of using flexible containment systems in the pharmaceuticals industry, it is now feasible to open the familiar inspection hatch and to inspect the screen in this way without any dust escaping. In addition, it is possible to replace the screen basket and exchange the dosing screw under containment conditions.

Additional Information
Interview with Frank Pahl, Head of Development, Azo
Screening Ignitable Bulk Materials

? Frank Pahl, is the cyclone screener suitable for use in production in zones where there is the potential for explosion? Can the machine be used to screen ignitable bulk materials?

Pahl: It is indeed correct to consider use in defined zones separately to the actual interior of the machine. The electrical components, as regards drives and sensors, are defined according to zones in the relevant requirement in conformance with Atex. Typically, on the inside of the machine zone 20 prevails with combustible products. Azo has a type examination in place for all its screeners for this use in compliance with EC directive 94/9/EC. This type examination specifies that products with a minimum ignition energy of MIE ≥3mJ may be screened.

? The regulations for explosion protection are subject to constant change.

Pahl: My colleagues and I follow amendments to the legislative framework for explosion protection very closely. The type examination therefore already satisfies the requirements of directive 2014/34/EU that comes into force in April 2016.

? It is also possible to screen products and dusts with lower minimum ignition energy using this cyclone screener?

Pahl: The figures from the type examination are to be observed with no exceptions. If the product’s properties are unfavourable, this may necessitate installing additional protection in and on the machine. In this case, we use inertisation of the internal chamber as an example.

? What assistance do you offer your customers when they put concepts like this into practice?

Pahl: Azo already offers expert consulting in the initial discussions about choosing and dimensioning potential systems for protection. This is how we were able in the past to plan alternative solutions for rendering hybrid mixtures inert (when combustible dusts and potentially explosive dust/gas mixes are present at the same time) in collaboration with our customers.

What is special about the DA machine type is that there is no need for an upstream dosing unit thanks to self-dosing. It is possible to adjust the integrated dosing screw’s dosing rate to match the specifications for the specific product using frequency converters. With the DA … Vario, the screeners throughput can be adjusted using a combination of different dosing screws with the screen module in order to accommodate very diverse products, screen capacity or mesh sizes.

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