Gas extinguishing system
Gas extinguishing system made in germany
T&B gas extinguishing systems for property protection are designed in accordance with BGI 719 and EN 13478. Fire detection takes place via flame and infrared detectors that monitor every area of the machine tool. In addition, the extinguishing system can be triggered via a manual call point.
A gaseous extinguishing agent is used because, unlike water, a gas also penetrates into concealed areas of the machine, i.e. it extinguishes in three dimensions. Fine spray extinguishing systems cannot guarantee successful extinguishing of fires behind obstacles (workpiece, tools, etc.).
Great extinguishing effect due to argon extinguishing
Extinguishing is preferably carried out with the inert gas argon, which offers the advantage, particularly in production areas with operating personnel, of not posing any danger to personnel while ensuring the greatest possible extinguishing effectiveness and can be returned to the environment after extinguishing without leaving any residue via simple ventilation. Escaping pressure waves and flames must be discharged in such a way that the machine operators are not endangered. The installation of the extinguishing devices is usually carried out by the manufacturer of the machine tool and requires in-depth specialist knowledge of the machine design. In addition to fire detection and extinguishing, the T&B BM 4-2G extinguishing control panel also alerts personnel via audible and visual alarms and monitors the enclosure doors, for example. This means that the machine cannot start up when the doors are open and the extinguishing system is blocked. The detectors and extinguishing agent supply are permanently monitored and the operating personnel are alerted in the event of a fault.
Preventing the spread of fire in extraction systems
As a rule, extraction systems are used to ensure that flammable coolant emissions do not accumulate in the machine tool during normal operation. However, this increases the risk of the flame penetrating directly into the pipework and spreading the fire to other production areas. Therefore, to prevent the spread of fire in the extraction lines, quick-closing shut-off dampers must be used to ensure that the machine tool is sealed off from the extraction system or vice versa in the event of a fire.
Gas extinguishing systems for machine tools
Machining centers for processing metals using flammable cooling lubricants pose a considerable fire hazard in production areas, especially when processing light metals. In addition to the actual working area of the machine, the transport area of the workpiece and the exhaust air duct are also at risk.
As early as 2013, the German Social Accident Insurance Institution for the woodworking and metalworking industries noted that the trend towards the use of non-water-miscible, flammable cooling lubricants is increasingly bringing the issue of fire and explosion protection on machine tools to the forefront for operators and insurers. [DGUV Information 11/2013]. This trend is continuing.
As early as 2013, the German Social Accident Insurance Institution for the woodworking and metalworking industries noted that the trend towards the use of non-water-miscible, flammable cooling lubricants is increasingly bringing the issue of fire and explosion protection on machine tools to the forefront for operators and insurers. [DGUV Information 11/2013]. This trend is continuing.
Gas extinguishing systems for filters
Ignition of the coolant/air mixture in the interior of the machine tool can result in violent flames escaping into the vicinity of the machine. While such fire incidents are often harmless, according to the employers’ liability insurance association, the lack of extinguishing systems has in many cases resulted in millions of euros worth of damage and seriously injured employees. In every case, however, there were lengthy interruptions to operations due to damage to the machine tool. The cause of damage is often a red-hot chip, spark or a tool that has run hot. The primary aim of any fire protection concept must therefore be rapid fire detection inside the machine and immediate activation of an extinguishing system.
T&B electronic’s protection concept for protecting employees and machines from fire and explosion hazards is described below.
The aforementioned measures are implemented by T&B property protection extinguishing systems and thus serve to protect machining centers. The gas extinguishing systems are designed in accordance with VdS 2380. The functional diagram is shown in Fig. 1. Fire detection takes place via thermal and flame detectors (1,2), which monitor every area of the machining centers. In addition, the extinguishing system can be triggered via a manual call point (3). When one of these detectors is triggered, the shut-off damper (5) is closed via the BM 4-2G extinguishing control panel 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 audible and visual alarm device (7, 8) alerts the operating personnel.
In contrast to CO2, there is no risk of argon splitting even at high temperatures. Argon can therefore also be used for extreme combustion processes, such as metal fires. The pressure relief device (9) has the task of relieving excess pressure caused by the ignition of a mixture or the inflow of the extinguishing agent in the working area of the machining centers. The pressure relief flap is usually installed in the ceiling area of the machining centers. The Employer’s Liability Insurance Association recommends ensuring that the pressure is relieved as directly and quickly as possible, that flames and hot combustion gases are discharged into non-hazardous areas and that there is no risk to machine operators.
If the lubricoolant/air mixture ignites, very high jet flames can escape when a pressure relief device is activated, posing a risk to the area around the machine. Therefore, there must be no flammable materials (wood paneling, insulation, etc…) in the area above the pressure relief flap. The device only opens briefly and closes again immediately after the pressure has been relieved.
Object protection of filters by gas extinguishing systems
Workplaces where dust or pollutant emissions occur are usually equipped with an extraction system and a filter. The ingress of glowing particles into this filter can cause the filter elements to catch fire. T&B object protection extinguishing systems are used to protect these filters. The most important prerequisite for effective fire protection is a holistic protection concept that is individually tailored to the respective application. A fire is detected in the raw and clean gas area of the filter using highly sensitive infrared and thermal detectors. This combination ensures maximum reliability and protection against deception.
Extinguishing is preferably carried out with the inert gas argon. With the greatest possible extinguishing effectiveness, there is no danger to persons and argon can be disposed of without residue via the existing ventilation system after extinguishing. The frequently used extinguishing gas CO2 is only recommended if the protected object is located outside buildings and there is no risk to persons. In addition, on-site relief surfaces reduce the pressure in the protected object to a safe level. The heart of a T&B object protection extinguishing system is the BM 4-2G extinguishing control panel. In addition to evaluating the detector signals, this control center takes over the necessary machine control (switching off the fans, closing the dampers in the raw and clean gas lines and, if necessary, in the filter discharge) and the control of the extinguishing process. The extinguishing gas flows into the protected area in a matter of seconds, displacing the oxygen down to a residual oxygen content individually adapted to the protected object, at which point the fire comes to a standstill. The system is designed in accordance with VdS guidelines 2380 and 3445 as well as DIN EN ISO 19353:2016. The T&B object protection extinguishing system complies with the requirements of the BGR 134 guideline of the employers’ liability insurance association.
