T&B extinguishing systems for building protection implement the above-mentioned measures and thus protect machining centres. The gas extinguishing systems are designed in compliance with VdS 2380. Fig. 1 shows the functional principle. Fire detection is by means of thermal and infrared detectors (1, 2) which monitor all areas of the machining centre. In addition, the extinguishing system can also be triggered by a manual alarm (3). When one of these detectors triggers, the butterfly valve (5) is closed via the extinguishing control unit BM-4-2G integrated in the compact extinguishing system (4), the extinguishing agent supply is activated and the extinguishing agent flows into the protected object via the nozzles (6). The acoustic and visual alarm (7, 8) alerts operating personnel.
When argon is used, there is no risk of the gas decomposing even at higher temperatures, unlike CO2. For this reason, argon can even be used for extreme combustion processes such as metal fires. The pressure relief device (9) has the task of reducing excess pressure caused by the ignition of a mixture or the inflow of extinguishing agent into the working chamber of the machining centres. The pressure relief valve is usually installed in the roof area of the machining centres. The employers’ liability insurance association recommends guaranteeing pressure relief as directly as possible, directing flames and hot combustible gases to non-hazardous areas and excluding risks to machine operators.
If a cooling lubricant-air mixture ignites, very high explosive flames can occur when the pressure relief system responds, which is a hazard for the area around the machine. For this reason, no combustible materials (wooden panelling, insulation etc.) may be anywhere near the pressure relief valve. The device only opens briefly and closes again directly once pressure has been relieved.