Problem solving Spark trap replaces wet pre-separator
at BMW, Munich, Germany Innovation for extracting explosive dusts Modern motor vehicle bodies are no longer made exclusively from steel. Bodywork construction increasingly involves the combined use of steel, aluminium and plastics in a hybrid mix of materials designed to reduce weight and improve functionality. This trend has had a major impact on all aspects of manufacturing technology, introducing substantial changes throughout the production process. One of these changes involves the extraction of process wastes such as sanding dusts during the machining and repair of vehicle bodywork. Aluminium dust is inflammable. A bodyshop mechanic sanding an aluminium body part may accidentally touch a neighbouring sheet steel panel. This can produce sparks which will ignite the aluminium dust. This is a job which requires a Type B1 unit, designed for vacuuming and extracting inflammable dusts. The vacuum unit should also be designed to ensure that it does not vacuum up the ignition source, the sparks. One of the well established ways of doing this is by using a wet pre-separator where the extracted material is passed through a wet medium. The principle is proven and effective but has a drawback. The wet pre-separator is larger than the industrial vacuum itself and this makes the complete unit difficult to handle and move around. For BMW, RUWAC developed a new vacuum unit which does without the wet pre-separator. The new unit has a 'spark trap' in place of the pre-separator . Housed inside a compact container, the spark trap employs a mechanical principle only and literally shatters the spark. The vacuumed material then passes through a 5-metre long damping section before it reaches the dust pan. Extensive testing at RUWAC and at the BMW Development Center has shown that the spark trap effectively and reliably prevents the vacuuming of ignition sources. BMW has another good reason for adopting this new technology. The frame and outer panels of a new super sports car just entering small-series production are almost entirely made from aluminium. BMW must therefore be in a position to offer its service workshops a safe method for handling the new material during bodywork repairs. The new RUWAC vacuum is ideal for workshop use. It can be used for dust extraction directly at the sanding machine or for general purpose dust vacuuming throughout the workshop. For general-purpose vacuuming the unit can work without the spark trap. The vacuum and extraction connectors are mechanically coded and therefore confusion-proof. |
