DSS027: Understanding the German VDI Standards for Explosion Safety with Dr.-Ing. Johannes Lottermann

In this episode of the Dust Safety Science Podcast, we interview Dr.-Ing Johannes Lottermann, Director of Explosion Safety at REMBE Safety + Control in Brilon‎, Germany, about the German VDI standards for explosion safety.

In addition to his work with REMBE, Johannes is a member of several VDI technical committees and currently the Chairman of the Scientific Technical Committee at INDEX, or Intercontinental Association of Experts for Industrial Explosion Protection. We would also like to point out that REMBE and Jeffrey Nichols, who was interviewed in Episode #23, were the first two supporters of the Dust Safety Science newsletter.

During the discussion, Johannes explains:

How the VDI standard compares with the ATEX standards commonly used in Europe
The different parts of the standard, which are broken down by equipment type
The ways that German regulations on combustible dust safety differ from those in other parts of the world
The differences between dust explosion and gas explosion

Towards the end of the interview, he reviews the worldwide challenges surrounding combustible dust regulation and emphasizes the need for a scientific approach to combustible dust safety in the workplace.

The German VDI Standard Explained

Johannes travels around the world and educates clients on explosion protection and safety. He inspects plants, carries out DHAs, and performs risk analyses to establish compliant safety measures. He also presents at industry events. Johannes is also very involved with the VDI safety standard used in Germany. VDI is short for Verein Deutscher Ingenieure, which is the Association of German Engineers.

Being part of the European Union, Germany works under the ATEX Directive, but the European approach is to allow every country to adopt its own guidelines. For combustible dust hazards, the appropriate standard in Germany is VDI 2263, which applies to certain types of equipment. For example:

2263.6 covers dust collectors, baghouses, and filters
2263.7 is directed at spray dryers
2263.8 is aimed at bucket elevators

Although not a law, VDI consists of state-of-the-art guidelines from German engineers, making it a recommended standard to follow.

Some of the different regulatory frameworks seem to separate combustible dust from other explosion hazards, such as gas or liquid, while others don’t. For example, the NFPA standards are heavily combustible dust-dependent while other authorities will state that an explosion hazard is an explosion hazard and the fuel type or phase doesn’t matter.

Johannes described dust and gas explosions as ‘evil twins’ that are both dangerous and need to be calmed down in different ways. He called dust explosions the more evil of the two. Dust-handling machines have a lot of ignition sources, but the danger is underestimated, which is one of the reasons why dust explosions can be a bigger challenge. He recommends a systematic ignition hazard analysis for both dust and gas hazards.

The European Approach to Explosion Safety

Johannes described the European approach to explosion safety as “very probabilistic,” meaning that it assesses the likelihood of an occurrence in an explosive atmosphere. For example, a dust zone categorized as Zone 22 is a place in which an explosive atmosphere is not likely to occur in normal operation but if it does, it will only persist for a brief period. Examples include leaks from poorly fitted lids. Even if the likelihood of the three explosion triangle conditions being met is remote, chances are rare that such a situation would be acceptable from a safety viewpoint.

He said that the approach in the Americas is more ‘deterministic’ and cited the example of the so-called eight cubic foot (250 liter) threshold for vessels. In the U.S., anything below that size would not require protection whereas in Germany, they would say that even a 100-cubic-meter silo with flour would not necessarily require explosion protection if certain preventative approaches are taken.

This approach also works the other way. There is a video (see resources below) of a creamer dust explosion in an 80-gallon drum of the type commonly put at the bottom of dust collectors. The lid was placed on top so that the vessel could not vent properly during the explosion, and the lid shot 40 to 50 feet in the air. This could certainly be a hazard depending on the system and facility layout involved.

The point is that when it comes to explosion safety, blanket statements and cut-offs can be dangerous because people are tempted to overlook or gloss over the likelihood of smaller-volume incidents. There may also be technical difficulties, such as problems venting a smaller vessel, but you can still take steps to prevent people from being injured if an explosion occurs.

Johannes pointed out that with ASTM, EN, or VDI, dust characteristics are tested in 20-liter spheres which are one-tenth of a cubic foot. Laboratories are then taking the characteristics from these small vessels and extrapolating them. The theory is that the expansion of an explosion is typically 10 times the volume of the vessel. With the eight-cubic-foot vessel, the impact of the explosion should only be four or five feet, and anyone standing beyond it should be safe. However, as Johannes says, “I don’t want to come to my colleague’s loved ones and have to say that someone died because the screw was flying off a vessel that was not supposed to explode.”

There is more to an explosion than the flame effect. Parts also rupture and create flying missiles, as the creamer explosion shows, and people can get seriously hurt or even killed under conditions that the blanket approach would deem safe.

Conclusion

When asked about challenges facing combustible dust safety, Johannes quoted Otto von Bismarck: “Laws are like sausages. It’s better not to see them being made.” Explosion safety is an engineering and a scientific discipline, and no regulatory topics should be passed on the basis of lobbyism.

REMBE has opened its Research and Technology Center, which is ISO 17025-certified, and recently carried out a lot of tests for INDEX. It also holds an annual event called REMBE® Safety Days, which spreads awareness of fire and explosion hazards in various industries: this year it will be held from November 19-20 and focus on safety in food and beverage industries.

If you would like to discuss further, leave your thoughts in the comments section below. You can also reach Johannes Lottermann directly:
Email: [email protected]
LinkedIn: https://www.linkedin.com/in/dr-ing-johannes-lottermann-07524162/

If you have questions about the contents of this or any other podcast episode, you can go to our ‘Questions from the Community’ page and submit a text message or video recording. We will then bring someone on to answer these questions in a future episode.