A food additives manufacturer faced the challenge of securing a new maltodextrin dryer installed in its research facility. In a laboratory and R&D environment, where small yet diverse batches of materials are processed, explosion risk is difficult to predict and requires a proactive safety approach.
A challenge we often encounter in industrial projects arose here as well: there was no technical documentation for the equipment to be protected. The client had only a single drawing available. How did we approach the process of securing the dryer in a newly built facility?
First Step: Explosion Parameters
Dust explosivity is not limited to the chemical or wood-processing sectors – the food industry is also highly exposed to this hazard. Products such as powdered milk, starch, cocoa, icing sugar and maltodextrin, despite their “safe” and everyday nature, can form highly explosive mixtures with air under the right conditions. Fine-grained dust fractions, high drying temperatures and the widespread use of filtration systems and pneumatic conveying all contribute to the formation of explosive atmospheres.
A lack of awareness of the hazard, or misplaced confidence in the “food-grade” character of these materials, often results in underestimating the risk. This is why a systematic approach to explosion protection is essential for modern process installations – both in production plants and in R&D facilities.
In this project, the explosion hazard was associated with maltodextrin. This seemingly harmless food-grade powder exhibits properties typical of St1-class combustible dusts. With a low Minimum Ignition Energy (MIE) of approx. 30–50 mJ and a low Lower Explosion Limit (LEL) of around 60 g/m³, it presents a high explosion risk, with a maximum explosion pressure (Pmax) of 7–9 bar. These parameters mean that even small amounts of maltodextrin dust can pose a serious hazard in industrial environments.
As the client was expanding its R&D centre, and maltodextrin drying was a core part of the planned laboratory processes, it became necessary to protect both the dryer and the adjacent dust filtration unit.
Second Step: Equipment Strength Assessment
Once we confirmed the maltodextrin was explosive, we moved to the toughest task. We had the material and the dryer but lacked technical documentation, so we could not determine how destructive an explosion in this specific machine might be.
We approached the challenge comprehensively. We began with a detailed survey of the existing dryer and an assessment of its resistance to a potential explosion. Explosion simulations were carried out to precisely determine the explosion load and its impact on the dryer’s structure.
Such simulations model extreme dynamic loads (shock waves and pressure surges), analyse the structural and material response, and the results are then interpreted in line with strict industry standards.
The findings allowed us not only to select the appropriate explosion protection measures, but also to identify areas of the equipment that required reinforcement. For example, we recommended strengthening the dryer roof with additional beams. We provided the client with detailed execution designs, enabling them to efficiently begin the necessary works.
Third Step: Explosion Protection Systems
In this project, we proposed an HRD (High Rate Discharge) system to protect the maltodextrin dryer. Its role is to detect and suppress an explosion at the very earliest stage, within fractions of a second. In addition, we installed a passive IsoDisc explosion isolation device to prevent flame and pressure from propagating into the room.
The protection concept was complemented by an EVN valve installed on the filter adjacent to the dryer. This passive explosion venting system rapidly relieves pressure while simultaneously extinguishing the explosion flame. Thanks to its simple yet effective design, the EVN valve protects equipment from explosion-related pressure damage without the need for a power supply or control system. It is a cost-effective and proven solution for applications where active detection is not required.
The decision to use the HRD system together with EVN and IsoDisc was based on an analysis of both the process characteristics and the limitations resulting from the lack of equipment documentation. The HRD system was selected for its extremely fast response time – suppressing an explosion within milliseconds protects the dryer even in the case of a highly dynamic St1 dust explosion. Importantly, it also enables active explosion isolation, which is essential where the dryer is connected to other process equipment.
The EVN and IsoDisc devices, as passive solutions, provide reliable protection at points where installing active systems would be uneconomical or technically unfeasible. This combination delivered a flexible and effective protection concept that ensures continuous plant operation without compromising safety.
Results: Safety That Enables Innovation
Thanks to our comprehensive approach and specialist expertise, the client received a complete solution delivering the highest level of safety. Not only were the legal safety requirements (ATEX Directive) fully met, but the company also provided its employees with the confidence and comfort needed to carry out innovative research work in the laboratory.