Controlling Complex Testing Systems for Filter Media

 1 July 2022
Precise Management of Testing Processes

Operating rooms and pharmaceutical production facilities have one thing in common: They require cleanroom technology to ensure patient safety and the quality of production environments. Topas is a technology leader in this field. When testing filter media, such as those required for air filters in cleanrooms, Topas relies on control technology from WAGO.

Cleanroom technology is the key technology in many applications. For example, it is used for medical treatments in operating rooms, in the pharmaceutical industry and in production facilities for microelectronics, where it keeps the quantity of airborne particles introduced into or created within the room as low as possible. This is essential in order in order to treat patients safely and protect products from harmful particles.

Qualification and Testing of Filter Materials

When it comes to purifying air, filters are the crucial component, so it is essential for the corresponding systems and their filters to be qualified and regularly inspected and for the results to be fully documented. Guidelines such as VDI 2083 and ISO 14644 specify testing methods and indicate a classification and a determination of concentration for the particle cleanliness of the air in cleanrooms and cleanroom areas. Air purity classes are determined on the basis of measured concentrations of airborne particles of various standardized sizes.

Stephan List also knows how crucial qualification and testing of filter materials and quality assurance for the filter testing process are. He is Division Manager at Topas GmbH in Dresden, where he is responsible for the manufacture of equipment and testing systems, as well as engineering: “We’re all about particle technology. We generate, measure and condition aerosols and manufacture the necessary devices, as well as complete testing systems. Our selection ranges from testing filter media and elements in the laboratory to procedures for regular filter testing at the shortest possible intervals during product monitoring in mass production of filters.”

This company from Saxony now has 60 different series devices and 20 types of testing systems for industrial users, research facilities and institutes and generates, conditions and analyzes test and reference aerosols. “The challenging part is that our customers usually come to us with very specific requirements. The applications range from motor vehicle filters and gas turbine filters to clean rooms in the pharmaceutical industry,” says Stefan Haufe, PLC and safety expert at Topas. As a result, there are also many different options for combining the sensors, actuators and analytics used.

The Highest Demands in Pharmaceuticals and Medical Technology

Applications producing substances that enter the human body are subject to the strictest purity requirements. And this strictness also applies to the cleanroom technology and its testing: In pharmaceutical and biotechnical production, it is essential to reliably prevent contamination by germs, microorganisms and harmful substances at all times. And demands are increasing in medical technology too: Whether implants or devices such as biosensors that continuously monitor blood lipid levels, they all require contamination-free production. While ISO class 6 or 7 was once sufficient for microtechnology cleanrooms, ISO 5 is now required more and more often, which permits only five nanograms of organic substances per liter of air. This requires filters and systems that capture not only particles, but also chemicals. In addition, electromagnetic effects and vibration are playing a bigger and bigger role. Therefore, measurement and testing technology must be effective on the scale of individual particle interactions.

We’re all about particle technology. We generate, measure and condition aerosols and manufacture the necessary devices, as well as complete testing systems.

Stephan List, Division Manager at Topas GmbH

Efficient Systems and Documentation

To perform the tests efficiently and document the results without additional effort, the Topas systems simulate real processes. In addition to synthesizing aerosols, the business model includes sample collection, preparation and characterization with sophisticated measurement technology. Adjusting the various process steps in a device to the test specimen (e.g., the filter material) and the substances to be separated is a complex process.

Optimizing control of the interaction within the systems, i.e. making it as precise and automatic as possible, and achieving reproducible results require the use of state-of-the-art control technology. “We chose Wago to supply the internal control and communication components many years ago. At that time, the focus was more on purchasing affordable devices with a wide range of capabilities,” says Stephan List. “But these days we also appreciate the stable development environment, the regular updates and, in general, the reliability of Wago as a partner. The scalability of Wago solutions also has been and remains a significant advantage.”

WAGO Control Technology in Control Cabinets

Control of Complex Inner Workings

Topas uses WAGO controllers for reliable control of sensors, measuring devices and actuators such as fans, dampers and valves. “We have to process a lot of signals, so our systems consist of many I/O modules and use large nodes. As a result, we have to support a large variety of different interfaces, which is another important reason that we always come back to WAGO I/O systems,” says Stefan Haufe.

Open Interfaces

For example, the PFC200 Controller is used in the AFS150 automatic HEPA/ULPA filter scan test stand. With this PLC, input and output devices are connected via the CAN, CANopen or Profibus DP protocols. Communication with the application software and the safety relays takes place over Modbus. The ETHERNET interfaces also support all common protocols such as DHCP, DNS, NTP, FTP and HTTP. SSH, HTTPS and FTPS are available for a secure connection.

And the PAF 112 test stand, used for quality testing of automotive interior filters per ISO 11155-2 with regard to adsorption/desorption of gaseous substances, also exemplifies the intensive cooperation between Topas and WAGO: In addition to rail-mount terminal blocks of various cross-sections and types, a network switch and electronic circuit breakers, the heart of the control system WAGO’s 750-891 PLC. It communicates with safety relays and application software via Modbus®. The sensors in the test stand are connected via serial interfaces.

The Key: The WAGO Controller

Identifying Leaks Precisely

“We use the PC for some steps, such as the test sequence, visualizing the processes, generating diagrams and the like, but for everything else, we have the corresponding WAGO PLC,” says Haufe, adding: “We don’t need real-time capability, but speed is still important. And the PLC’s short response time supports precise identification of problem areas or leaks. In general, we value the WAGO system’s flexibility for complex applications,” says Haufe. In the end, the combination of WAGO components with Topas know-how ensures cleanroom production of countless products and the highest quality standards in the production of a wide variety of filters.

For upcoming projects, we’ve already decided to use WAGO’s 750-8212 Controllers, which are equipped with faster processors and more working memory. Another important feature of the controller: the digital rights management, which allows functions to be extended individually for a wide variety of projects according to the specific requirements. Through the licensing mechanism (DRM), software applications and interfaces can be activated later on. “For the near future, we can already identify specific projects where these functions will be useful. You can definitely expect more exciting developments,” concludes Haufe.

Out of the Box: Air Purification

The influence of indoor air on human health has been known for a long time; it also became a key issue in the discussion about (re)opening schools during the COVID-19 pandemic. By rapidly developing mobile air purification devices, Miele, a family-owned company, hoped to help many families by improving health and restoring a degree of normalcy to their everyday lives. Thanks in part to outstanding collaboration with WAGO, the project has been a complete success.
MM-192878_reference report_Compact_Miele-AirControl_Miele_9_2000x1125_.jpg