Customer application 11 May 2022
Modularity in Hazardous Areas

Filling, sealing and testing all types of aerosol cans is what Pamasol Willi Mäder AG in Pfäffikon, Switzerland does best. The safety of their machines is guaranteed by the WAGO Ex i Module, which offers several key advantages.

The Benefits in Detail:

The modular system design minimizes the footprint, since only as many modules as actually are needed are attached.
The coupler’s multiple connectivity options and various certifications allow flexible use of one system for different markets and their requirements.
The long-term availability of these products or compatible alternatives allows defective modules to be replaced even after twenty years or more.

When Philipp Bruhin explains Pamasol’s business model, it does not sound particularly complicated. “We fill the container with a product, fit the valve on top and pump in the gas. Then we test it in a water bath, and finally we attach the spray nozzle and cap,” explains the head of the electrical department.

Explained this way, it does not sound terribly difficult, but it takes decades experience to master the process perfectly. Since it was established in 1965, Willi Mäder AG has perfected this principle. “Nowadays, we build a custom solution for each container type and offer a complete process, from empty containers all the way to filled and tested containers, including the caps,” says Phillip Bruhin, describing his employer’s expertise and adding: “We fill all types of products very precisely and with a very high degree of consistency.”

Process Challenges

It’s not quite as simple as it sounds at first. As an example, Philipp Bruhin describes the valve that has to be fitted atop the spray can and pressed on. If the machine does not press the nozzle on with enough force to form a leakproof seal, the propellant just vaporizes and leaks out. To prevent this, the operating pressure must stay within a specific range during crimping, as the sealing process is called in the aerosol industry.

Yet another challenge is the quality and tolerances of the spray cans. Some manufacturers find it hard to keep the height exactly the same during production, so additional engineering tricks are required is to detect and compensate for these differences when placing and crimping the nozzle. The trend towards thinner-walled containers to conserve materials also demands intelligent solutions to avoid producing large numbers of defective items.

With the Ex i Modules, we can
react very quickly to the needs of the particular market.

Philipp Bruhin, Head of the Electrical Department

Propane-Butane Requires Redundant Safety

Even just the example of placing and fitting the valve shows how much knowledge and experience is required in order to become established as the market leader. What role do WAGO’s Ex i modules play in all this? The answer to this question involves a great deal of knowledge and consistent attention to meeting customers’ needs. As Phillip Bruhin well knows: “Whenever you hold a spray can and press the nozzle, you expect the product to come out with the same pressure.”

The best way to achieve that is by using appropriate gases. There are limits to the use of normal breathable air for this purpose: As more product is expelled, the air volume increases and its pressure decreases. Propane-butane behaves very differently: With this explosive mixture, the pressure depends primarily on its temperature rather than its volume.

Mechanical engineers also take advantage of this physical phenomenon – pressure increasing as the temperature increases – when testing the spray cans. After filling, they are immersed in a 60 °C (140 °F) water bath for close to three minutes. This time span is enough for the pressure to double – if the spray can is not precisely sealed, a rising stream of bubbles quickly indicates the defect.

But back to the propane-butane mixture used: Although it is an ideal propellant, it is also extremely explosive, as mentioned above. That is why Pamasol Willi Mäder AG equips each of its systems with ventilation as a standard feature to neutralize escaping gases. “Even then, you still have to expect that an explosive mixture might arise, so we rely on redundancy,” explains Philipp Bruhin. This family company guarantees redundant safety by using Ex i components.

A Decentralized Approach for Hazardous Areas

Various manufacturers offer Ex i components, but ultimately they all have one thing in common: They prevent spark formation even when positive and negative poles come together, making them suitable for environments where explosive gases or mixtures can escape, for example.

WAGO’s Ex i modules offer this property and also let Willi Mäder AG use a modular principle in the design of its systems. “We start with a decentralized design and attach the electrical technology directly to the machine. Therefore, whether the control cabinet is for two machines or five, it’s always the same size,” says Phillip Bruhin, describing the procedure. Even though this approach is already widespread in mechanical engineering, suppliers like Pamasol are only slowly discovering it for themselves – simply because there hadn’t been many solutions available for hazardous areas

The possibility of decentralized electrical technology is something Phillip Bruhin values highly in WAGO’s Ex i modules. He’s also impressed by the variety of modules available for safety applications, as well as the coupler’s communication capabilities with different controllers. While Pamasol mainly employs the PROFINET^® communication protocol on the European market, the American market mostly requires ETHERNET/IP™.

The same applies to the most important certifications Ex i modules come standard with. The modules can be used in Europe, where ATEX compliance is required for use in hazardous zones, as well as in North America, where UL is the standard. “The variety of communication options and compliance with various standards allow us to react very flexibly to the needs of the particular market,” says the head of the electrical department.

No Additional Safety Tests during Commissioning

The system used previously did not offer this decentralized flexibility; it only could communicate via PROFIBUS^® and was designed exclusively for use in control cabinets. Furthermore, since it is only available with 16 or 32 modules, it required a corresponding amount space on the DIN-rail. Erich Bellmont, head of the workshop and the sales department, identifies another advantage: “With WAGO, we attach exactly the number of modules we need.”

Since the Ex i modules allow implementation of decentralized concepts, commissioning is faster and easier too. The machines are fully tested at Pfäffikon and sent from there directly to the customer, who can put them into operation immediately. “Since there’s nothing left to attach, no on-site safety test is necessary,” says Erich Bellmont, and concludes: “We only need to connect the power and ETHERNET, and it’s ready to go.”

Contact

Walter Simione

Area Sales Manager for Industry
Southeast Switzerland / Ticino Region
+41 (0)26 676 73 81

Email address: walter.simione@wago.com

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Customer application 11 May 2022 Modularity in Hazardous Areas