Explosion Isolation is absolutely necessary for a comprehensive safety concept. Without explosion isolation, the safety concept is not just insufficient, it also represents wasted money for operators, because: Throughout the industry, vessels, silos and other parts are often connected to each other by pipelines. If a dust explosion occurs in one equipement, this also enhances the risk of flames and pressure propagation to other parts of the plant. Pre-compression and flame jet ignition exacerbate the explosion severity in interconnected vessels. The result is a series of secondary explosions that may cause even more catastrophic damage.
An explosion isolation system prevents deflagrations from propagating and thus minimises the effects of an explosion. Adjoining plant components are optimally protected. A distinction is made between active and passive systems:
Passive isolation systems such as explosion isolation flap valves make use of the overpressure of the explosion for their operating principle:
Passive explosion isolation – this is how it works
Passive explosion isolation systems respond purely mechanically to the propagation of pressure through its constructive design. Under normal operation, an explosion valve in a pipeline is kept open by the available flow. When 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.
One function, different requirements
Even if the function of an explosion isolation flap valve is size-independent, the requirements for a wide variety of processes and industries vary greatly. While in the pharmaceutical and chemical industries in particular explosion isolation flap valves are typically only installed in nominal pipe sizes up to DN 400, especially on decentralised aspiration systems of the food industry, for example, larger nominal pipe sizes between DN 450 and DN 710 for central dust extractors can quickly become necessary. In the grain, wood and heavy industry, nominal pipe sizes from DN 800 to DN 1250 are mainly applied.
Optimum fulfilment of requirements instead of one-for-all
The standard EN 16447 defines the general requirements for explosion isolation flap valves. Like any standard, it can only provide general recommendations and specifications, but cannot address every application in detail.
Obviously, however, an explosion isolation flap valve DN 250 used in the chemical industry must meet different requirements than its DN 1250 counterpart installed in a grain or wood processing plant.
While the first application above all requires a high-quality design, the operators of grain mills or particleboard plants with their characteristic large pipe diameters want safety devices that are as easy to handle as possible.
The Q-Flap RX™ explosion isolation flap valve, a joint development of the explosion safety specialists REMBE (Germany) and RICO (Switzerland), offers three different design versions. Developed on the basis of many decades of experience the two companies have accrued with regard to the different customer requirements, the nominal pipe sizes from DN 140 to DN 710 feature an inspection flap, the largest nominal pipe sizes (up to DN 1250), on the other hand, have a modular design so that maintenance and servicing can be carried out easily and thoroughly.
Through the swing ´n slide closing principle integrated into the nominal pipe sizes up to DN 710, the valve blade not only rotates into the closed position, but also slides horizontally into the closed position at the same time. This ensures an even more reliable sealing of the entire cross-section.
In addition to the features mentioned above, the Q-Flap RX™ enables high KSt values, flexible installation distances and maximum strengths.
Fig. 1: Q-Flap RX™ explosion isolation flap valve