Refurbishment with explosion protection: an engineering project at the Mönchaltorf site

On a wintry day, two technicians are inspecting large, grey industrial units outdoors. Modular units are connected by insulated pipes and are covered in patches of snow. A metal ladder stands by whilst they check their documents.

Two people are clearing snow from a roof. One, wearing a pink jacket, is using a blue shovel, whilst the other, wearing a black jacket, is using a red one to clear a path. In the background are snow-covered industrial machinery and a snow-covered forest.

A bright room with U-shaped, white metal frames for laboratory tables or workbenches, running along the window front and one wall. Beneath the windows: dark radiators and a power strip. At the front, a makeshift wooden frame.

A smiling man wearing glasses and black work clothes is walking on snow-covered tarmac, holding an orange snow shovel. In the background, under a overcast sky, stand a large red crane lorry bearing the inscription ‘FLOCK KRAN’ and green waste skips.

Update from Mönchaltorf: Between explosion protection, PostBus air volumes and frozen gravel

February 9, 2026 News

9,000 cubic metres of air per hour – explosion-proof right up to the roof

Intensive refurbishment work has been underway at the production site in Mönchaltorf since December. At the heart of the project is a new, explosion-proof ventilation system with heat recovery, which poses considerable challenges both technically and organisationally. What sounded like a straightforward installation quickly developed into a project involving many stakeholders and special requirements. The most important feature of the new system is explosion protection. The entire ventilation system has been converted and redesigned accordingly. It is now installed on the roof and moves around 9,000 cubic metres of air per hour – including heat recovery. To achieve this, massive ventilation ducts had to be routed through two storeys up to the roof. Each individual duct run brought with it additional requirements: All wall and ceiling penetrations were professionally cut, sealed back up – and, of course, fitted with fire-resistant cladding. This presented a challenge not only for the builder but also for specialist ventilation technicians, a ventilation engineer (affectionately known in-house as ‘Schnude’ – the reason remains a secret) and the specialists from 7air responsible for the heat recovery system.

A construction site in winter: when gravel freezes and snow shovelling becomes a necessity

A winter construction site means one thing: patience. First of all, new floor slabs had to be laid on the roof. The problem: frozen gravel, freezing temperatures and limited time slots. In some cases, work could only begin in the afternoon, if the surface was even workable at all. At the same time: shovelling snow. On Sunday, Sarah and Silvan Lämmle personally ensured that paths remained clear, areas accessible and work could continue at all – a detail that is rarely factored into planning but is crucial in reality.

Modular design: the system as a technical jigsaw puzzle

The ventilation system itself consisted of numerous modules. These were delivered individually, dismantled, partly retrofitted, partly replaced and then reassembled. An industrial-scale jigsaw puzzle – with explosion protection, fire protection and heat recovery adding further layers of complexity. To get the whole thing onto the roof in the first place, a special jib crane was used, operated by the crane operator from Flück. Two electricians, a control engineer for the entire control system, a software specialist for reprogramming, and a heating specialist for all the pipework ensured that, in the end, not only was everything installed, but that it also worked together correctly. And then there was Walti: he made sure that tools were available, that the ground was gritted, that it wasn’t icy, and that the crane could be properly stabilised. (Incidentally: Stephan Lämmle’s father-in-law – experience sometimes trumps any specification sheet.)

Planning meets reality – and not everything fits straight away

As is so often the case with complex refurbishments, not everything went to plan. Some cables that had been laid during the preparatory phase later failed to meet the requirements and had to be removed and replaced. The necessary correction was not exactly a mood-lifter for Stephan Lämmle. The biggest challenge at present is the declaration of conformity, which must be submitted to the authorities. It confirms that all requirements have been met – a formal step that is just as technically demanding as the conversion itself.

Supply bottlenecks, detours – and a missed deadline

Not everything was within our control: A Swiss manufacturer of fire protection insulation for ventilation ducts suffered production damage. The result: a last-minute change of supplier, rescheduling and additional coordination. And amidst the daily grind of the refurbishment, other things sometimes fell by the wayside: Stephan Lämmle missed his test appointment at the Road Traffic Authority. Priorities can sometimes shift quite dramatically when there’s an explosion-proof ventilation system on the roof.

Outlook: Tank room, laboratory and many firsts

Alongside the ongoing work, preparations for the explosion-proof tank room are already under way. Work is also continuing in the laboratory: assembling furniture, intensive preparation – and a great deal of coordination required. For many chemists, a project of this kind is uncharted territory. The high level of complexity, the multitude of decisions and the interdependencies were at times nerve-wracking, but were managed collectively.

Conclusion: Technology, teamwork and a bit of winter resilience

The refurbishment of the ventilation system in Mönchaltorf demonstrates just how much coordination, expertise and flexibility are required to make a production site fit for the future. Between frozen gravel, explosion protection, cable adjustments and 9,000 cubic metres of air per hour, one thing has become clear: projects like this only work when many specialists work hand in hand – and when someone spreads salt in good time.