Avoiding an explosive environment seems to be the most obvious protective measure - but not all processes are suitable for it. Aluminum processing with MQL, for example, is interrupted during the cleaning of filter elements. During cleaning, no ignition source can gain entry. Furthermore, the suction air duct is monitored by a spark sensor. If an ignition spark entry is detected, the PLC can be set to prevent the next pending cleaning of the filter elements, thereby averting an explosive situation.