cpp SPECIAL POWTECH A special mesh filter in the Q-Rohr cools down any flames, preventing both flames and pressure from emerging Quench valves, open and closed: these valves are activated in response to a rise in pressure or theformation of flames Flameless venting If a plant is situated within a building, however, explosion vents are not suitable for pressure relief purposes, as the safety area around them is inadequate to relieve the emerging dust and flames. Such an arrangement would pose an enormous safety risk to humans and machinery. This problem is often solved through the use of vent ducts, which channel the spread of an explosion to the outside. The disadvantage, though, is that these ducts rule out process-optimised plant design and are usually very expensive: the greater the distance between an explosion and its source, the higher the pressure which the vent duct and the plant need to withstand. This results in higher (manufacturing) costs per vent duct. Flameless venting, by contrast, is an option that is both economical and effective. Different manufacturers employ different flameless venting technologies. The special mesh filter that is used in Rembe’s Q-Box or Q-Rohr cools down any flames efficiently, preventing both flames and pressure from emerging, and ensures particulate retention. The typical increase in pressure and noise that accompanies an explosion within a building is reduced to an almost imperceptible minimum, thus protecting both people and machinery. In addition to the special stainless steel mesh filter, the Q-Rohr and Q-Box each have an explosion vent with an integrated signalling system that alerts the process control system if the explosion vent opens. Explosion isolation In a production facility, the individual parts of the plant are always connected by pipelines. The purpose of explosion isolation is to ensure that the pressure and the flames cannot propagate, so that any adjoining parts of the plant are protected. A distinction is made between active and passive isolation systems. An active system is alerted to an explosion at an early stage when the explosion begins to develop. This is done using sensors or detectors which register the rise in pressure or theformation of flames and respond by activating the relevant isolator, e.g. a quench valve. Passive isolation differs in that it responds purely mechanically to the spreading or loss of pressure on account of its structural characteristics. This also applies to explosion valves. During normal operation, an explosion valve in a pipeline is kept open by the flow. If an explosion occurs, the valve is closed by the spreading of the pressure front, thus effectively preventing the pressure and the flames from propagating any further. Explosion suppression Explosion suppression is another constructional precaution in addition to the methods mentioned so far. It means eliminating the explosion at its onset. This is made possible by detectors with sensors which register the presence of sparks or flames and immediately trigger the opening of tanks containing an extinguishing agent (also installed in the system). A highly effective extinguishing agent is released within milliseconds, nipping the explosion in the bud. If required, an explosion suppression system can also be used for explosion isolation purposes. www.cpp-net.com Online search: cpp0317rembe Hall 3, Booth 244 AUTHOR: DR. JOHANNES LOTTERMANN Director Explosion Safety, Rembe 10 cpp 03-2017
SINTERGLASS Borosilicate glass 3.3 with high chemical, thermal and mechanical resistance: Custom sintered elements made from VitraPOR ® are characterized by their neutral properties and open-pore structure. Even forthe most unusual applications. Our VitraPOR ® glass filters are heat resistant up to 540°C and can withstand most acids, alkalis and solvents. They can be used in many chemical, pharmaceutical, biological and technical processes, and they are produced in porosity classes from under 1 μm to over 500 μm. VitraPOR ® glass filters are always produced according to international standards, as are the custom-made solutions available in many shapes and sizes. Made in Germany www.robuglas.com cpp 03-2017 11
