Since April 26, 2016, the new regulation TRGS 727 became valid¹. Hoses, which are intended to be used in hazardous areas, have to be certified according to the TRGS 727. According to the now valid TRGS 727, for aspiration and transport of inflammable bulk materials and the use in hazardous areas, the user should choose certified hoses.
NORRES  already offers a solution: certified suction and transport hoses from the PUR-AS and FOOD-AS-product line for aspiration and pneumatic transport of inflammable bulk materials.

Our FAQ about the TRGS 727

¹ gmbl-online.de/ausgaben.html