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Smoke generator for practices and trials in tunnels

For drills and trials in newly constructed tunnels, fire services in Hesse wanted a smoke generator that would allow them to simulate the behaviour of fire smoke during a major incident in a tunnel as realistically as possible. But such a device did not exist until now. This lack was shown in 2019 by a market analysis conducted by district fire inspector Christian Sasse (Werra-Meissner district). After this analysis, development work began on the FT-SDAN 500 tunnel fire simulator, which Volker Heerdt from the Hessian State Fire Service School (HLFS) presents in this article.

In three years, from market analysis to the first deployment

A working group developed the specifications for the smoke generator, but initially, no manufacturer responded to the 2020 call for tenders. «It was really very, very difficult until a company was found,» says Volker Heerdt. 2021 saw the start of cooperation with Firefog Technology, which then delivered the Tunnel Fire Simulator in the summer of 2022. The new device passed its first test in October 2022 during a drill in the 4.2 km long Hirschhagen Tunnel, the longest tunnel on the A 44 to date and Germany's second-longest motorway tunnel.

Smoke generator in operation during a drill in the tunnel
The behaviour of the preheated artificial smoke during the test run in the tunnel. © Hessian State Fire Service School

Technical details are tailored to the equipment of the fire services

The mobile smoke generator weighs 2.2 tonnes together with the tandem-axel trailer on which it is mounted. It can be towed, for example, by a crew transport vehicle with a corresponding trailer coupling. A 60 kVA power generator is required for smoke production, corresponding to the power of the mobile emergency generators commonly used in Hesse's fire services to feed power to buildings.

Smoke generator on tandem-axel trailer
Company founder Michael Jordan decodes the name of the smoke generator: «FT stands for Firefog Technology, SDAH for special trailer (in German: Sonderanhänger) and 500 for the production of 500 000 cubic metres of artificial smoke per hour». © Firefog Technology.

300 litres of smoke fluid for several hours of operation

The smoke generator, with its supply of 300 litres of smoke fluid, can be operated continuously for three to four hours, explains Volker Heerdt. The generator is controlled directly on the device or via a remote control with a range of up to 500 metres. The first tests showed: One tunnel tube can be filled with smoke in a short time. The heated artificial smoke rises first. «It doesn't decompose very quickly and doesn't sink very quickly to the ground either». After the first tests, Volker Heerdt's impression was: The behaviour of artificial smoke is similar to that of real smoke.

Artificial smoke generation in the tunnel
Volker Heerdt's observation from the first drill: «The artificial smoke leaves no residue, for example, on turnout gear, and no oily, slippery residue on the floor». © Hessian State Fire Service School

Hesse fire services can lend the smoke generator

The 110 000 Euro expensive Tunnel Fire Simulator at the HLFS can be borrowed by fire services in Hesse for drills. So far, there are no considerations or regulations for lending to fire services outside of the federal state of Hesse. The manufacturer has included the smoke generator in its regular programme as a novelty. The device is explained in a German-speaking video clip from Austria TV, and an excerpt from the drill in the Hirschhagen Road Tunnel is shown. Another video clip shows the behaviour of the artificial smoke in the tunnel.