Explosion protection expertise means safety – at the R. STAHL Expert Forum

Manfred Kienlein from DEHN SE + Co KG provided a flash of inspiration with his presentation at the Expert Forum. Measures to prevent damage caused by lightning and overvoltage are key components in concepts to protect buildings. They form the basis for preventing fires, protecting people against injuries and important, delicate technology against damage – protection objectives which are also founded on standardised requirements and legal regulations.

Is an explosive atmosphere present, does this pose a hazard due to local and operational conditions, and is there the risk of sparks forming in these areas due to lightning, is a lightning protection system needed? Why? Because lightning, as an ignition source, is hazardous. A lightning protection system is also needed if there is a risk of interactions.

Stefan Ditting from HIMA Paul Hildebrandt GmbH began his presentation on "Cyber Security and Functional Safety" by pointing out the irony of automation: "The more we automate, the less attention we pay." So the paradox of automation is "that the requirements placed on the user increase as automation becomes more efficient. Although people have less to do, what they do is more critical." This is why people still have an important role to play in order to prevent cyber security and functional safety from negatively impacting each other.

Rico Schulz from R. STAHL explained why it makes sense to switch to LED technology, even though the EU's ban on T8 fluorescent lamps does not apply to hazardous areas:

• The costs associated with T8 lamps are going up.
• Energy costs are high and are expected to increase further.
• T8 lamps are expensive to dispose of.
• The long service life of LEDs reduces maintenance costs.
• LED lighting is environmentally friendly at a time when legislation on environmental protection is becoming increasingly stringent.

Ventilation is part of primary explosion protection, while secondary explosion protection plays a role when selecting the right type of ventilation. Dietmar Stockburger from Maico Elektroapparate-Fabrik GmbH prepared many practical examples for the Expert Forum to illustrate how to implement various types of ventilation solutions, including dilution ventilation and transverse ventilation.

Following this, attendees paid close attention to the presentation given by Dr. Martin Thedens from the PTB in Braunschweig, as he gave them insights from the field of standardisation.

Sven Seintsch, Bilfinger Enineering & Maintenance GmbH, also shared his experiences and predictions for the future. He addressed the trending topic of Ethernet-APL. Ethernet Advanced Physical Layer (Ethernet-APL) is the new 2-wire solution for Ethernet, based on IEEE and IEC standards. This allows processing systems to be completely digitised – from the devices in the field, all the way to the control room. The new technology is also becoming established in hazardous areas: Ethernet-APL supports the intrinsic safety "i" type of protection, therefore enabling Ethernet access in hazardous areas up to Zone 0. Another advantage of digitalisation lies in the wide variety of options for process monitoring and diagnostics. In this way, users can optimise the availability of their systems. The audience proved to be very interested in this topic – and therefore also in the presentation given by Gerd Niedermayer from BASF SE, which was packed full of his own experiences.

BASF set up an Ethernet-APL test laboratory back in 2019 and is planning to install the first Ethernet-APL devices in a chemical tank terminal next year. There's no denying that the advantages of Ethernet-APL are impressive:

• Ethernet-APL creates a strong, continuous Ethernet connection, from devices in the field all the way to the control room, enabling vertical and horizontal integration throughout the entire system.
• For the first time, intrinsically safe Ethernet is possible as far as field devices in Zones 0, 1 and 2.
• Ethernet-APL brings high data rates of 10 Mbps into the field and supplies the field devices with intrinsically safe power via the network – over a distance of up to 1000 metres.

Niedermayer is certain that "the future belongs to Ethernet-APL", so it came as no surprise that the Expert Forum provided the impetus for further discussions and initial plans for implementation.

Are maintenance technicians sometimes the cause of fires? "No," is the response from Axel Heuwinkel, Axalta Coating Systems Germany GmbH & Co. KG. "But sometimes their work is one part of a chain of events that can lead to an accident." Heuwinkel provided plenty examples of this:

• Deflagration and fire in a container stirring device.
• Fire in a dissolver, spreading to the production system.
• Deflagration in a container cleaning system.
• Spark formation with smoldering fire at a ventilation system.
• Fire at a tank farm for solvent.
• And the list goes on.

The causes may vary. For instance, even just introducing new products with different physical properties, replacing an electric motor with a higher-power one, or higher speeds in systems are all it takes to cause an accident. This means that maintenance is one of the most important components of explosion protection.

The series of talks at the R. STAHL Expert Forum continued with a focus on practical applications. Rainer Hahnkemeyer, INTERTEC-Hess GmbH, explained the benefits of protective systems for delicate components that are made from GRP and used outdoors. These are lightweight, robust, resistant to corrosion and fire, durable and recyclable.

At present, public discourse is mainly focused on the opportunities which hydrogen will open up in future as an energy source and raw material. However, in many cases not enough attention is paid to risks and solutions for reducing them to an acceptable level. For example, explosion protection in particular gives rise to some unique challenges which Ugur Ünal explained at the R. STAHL Expert Forum.

Under normal conditions, hydrogen is a colourless, odourless gas. It is not toxic and causes no damage to the environment. At a temperature of 0 °C, it has a density of 0.089 g/l. Hydrogen therefore dissipates quickly in open air, as it is 14 times lighter than air, which has a density of 1.29 g/l.

However, hydrogen molecules are extremely small. This means that hydrogen has a high diffusivity, even through metallic materials. For instance, hydrogen atoms can lead to metal becoming brittle at grain boundaries or defects. This gives rise to unique challenges when it comes to the tightness of hydrogen equipment – albeit challenges that can be entirely overcome using technology.

Hydrogen and oxygen can form an explosive mixture (oxyhydrogen). From a safety perspective, the extremely wide explosive range of this mixture, from 4 vol.% (lower explosion limit, LEL) to 77 vol.% (upper explosion limit, UEL), is of particular interest. The minimum ignition energy of 0.02 mJ is among the lowest; there are only two other gases – acetylene and carbon disulphide – alongside hydrogen in the most hazardous ignition group, IIC. The relatively high ignition temperature of 585 °C appears to be inconsistent with the low ignition energy. This discrepancy is due to hydrogen's high thermal conductivity. Since the net influx of heat is always critical for an explosion to be triggered, only very hot surfaces and long dwell times are able to transmit enough heat into a hydrogen-air mixture to cause ignition.

Additionally, a hydrogen-air mixture is also different from other explosive mixtures due to its extremely high flame speed, which is around eight times higher than that of a methane flame. When used deliberately, such as in rocket propulsion systems, this property generates huge momentum (mass multiplied by flame propagation speed). However, unwanted and uncontrolled hydrogen explosions have extreme destructive power.

"This is why effective protective concepts and explosion protection are important when handling hydrogen – not to mention the fact that accidents risk making hydrogen less acceptable to the general public," explains Ünal. Possible measures include, most importantly, ensuring that the systems are tight and that effective ventilation is in place to prevent concentrations higher than 1%.

What should you do when a prosecutor comes for you? This question was asked by many attendees at the Expert Forum, who were looking for answers. These were provided by Dr. Christoph Skoupil from the Gleiss Lutz law firm. With his handy tips, visitors to the event are now prepared for the "worst-case scenario".