Cyclone Screener for APIs Screening API Without Exposure: How to Ensure Containment in Screening and Maintenance
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.
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.
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.
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.
The inspection hatch for checking the screen cylinder can be opened using a glove integrated in the flexible liner. The screen cylinder can be rotated manually by almost 360° and, thanks to the built-in light, it can be inspected for damage or contamination through the film. Once inspection has been completed, the inspection hatch can be closed again using the film gauntlet. Using this procedure means that the operator has no contact with the high-risk substance in the machine at any time whatsoever.
Replacing the screen
If any damage to the screen fabric is found during the screen inspection, this will necessitate replacing the damaged screen. This procedure can also be carried out using liner technology without any contact with the screened product. If the machine has stopped, the drive unit for the screen rotor is removed from the housing lengthwise together with the screen cylinder. The weight of this unit is supported by an extraction device. The plastic film system that was attached when the machine was fitted is deployed in this process; it forms a tubular working space, in which the screen cylinder and the screener rotor are located.
By using appropriate double-crimp-and-cut techniques, it is then possible for the operator to remove the used or damaged screen inside the plastic liner and to install the new screen while using a new liner, also within a protected environment. The use of a new liner prepares the machine for further operation and for the next screen replacement.
Replacing the dosing screw
The dosing screw conveys the product to the screen cylinder in a continuous process. The speed and thus the dosing rate can be adjusted using a frequency converter, depending on the particular product characteristics. To make adjustments to the range of dosing rates, it is possible to change the dosing screw geometry or to vary the speed with the frequency converter. The machine also allows for the dosing screw to be exchanged under containment conditions. The machine is opened using an extraction device in the same manner as for screen replacement. A film liner provides reliable protection to stop dust from escaping.
Cleaning the machine
A washing system is used to clean the inside of the machine with water. Dust particles are flushed out; any remaining particles in the machine are wetted with water and thus bound inside the machine. After dismantling the screw, the built-in glove system can be used to clean the contaminated inner walls of the machine with appropriate cleaning instruments.
Thanks to the DA … Vario Containment cyclone screener, the familiar advantages of Azo’s patented screener with separate drives for the rotor and dosing sides are combined with film liner technology from flexible containment systems. The outlay for wearing full body protection can be reduced for plant operators. Dust is reliably prevented from escaping during maintenance and inspection work. This means containment for operation as well as maintenance.