There is a serious risk of dust explosions with industrial processes that handle combustible dusts. Operators of these processes need to take preventative measures, one of which is to use explosion-proof dust collection systems.
When designing extraction systems to control combustible dusts, special attention needs to be given to the location of the dust collectors. The most common method of explosion protection for such installations is to release the explosion pressure through explosion vent panels to the outside of the building. The international ATEX and NFPA standards recommend the placement of dust collectors outside the premises where possible. However, the distance between the dust collector and the release area outside are in many cases too long, or the release area does not allow safe venting of an explosion due to the potential proximity of people, other equipment or properties. For such cases, explosion protection solutions that are customized and allowed to be installed inside the plant are needed.
Nederman can deliver flameless explosion venting for indoor use on versions of Nederman dust collectors MCP, MEP, LCP, LBP and FlexPAK and FlexFilter. Always reference the use in relation to product explosion properties and the extracted dust.
The flameless explosion venting devices provides a safe release of the explosion pressure, as well as of the absorption of the released energy that spreads during a dust explosion in the confined space of the dust collector. It prevents the transmission of explosion and flame energy through the blast discharge panel's release opening, thereby protecting both workers and equipment in its vicinity. However, even with the safe release of the explosion pressure, a safe area must always be defined to ensure safety in the event of an explosion.
This technical solution complies with the international ATEX standards. The flameless explosion venting devicesis designed in accordance with the requirements of EU standards and work with organic dust with an explosion index of Kst <300 Bar * m/s.
How does the indoor dust collector work?
If the operating pressure inside the dust collector is exceeded, a vent membrane will open into the body of the flame arrester, thereby releasing pressure from the dust collector. In this way, the dust collector will be exposed to a lower pressure, which it can withstand without being destroyed. When determining the quantity and type of flame arrester for a protected device, it is necessary to comply with the industry calculation rules and the ATEX directive.
The figures show the four stages of explosion development inside a flame arrester. At the first stage, a vent membrane opens and the explosion propagates inside, in the second stage, the explosion spreads to the entire volume of the flame arrester and the pressure is released through the grids, in the third stage, the flame collapses inside the flame arrester, and in the fourth stage, the flame completely disappears.
How to install the flameless explosion venting devices?
In front of the open surface of the flame filter, a safe area of 0.75-3 m from the device must be defined to ensure that no one will be affected by noise, smoke or steam in the event of an explosion. Specific parameters are indicated in the technical documentation. Entry to this safety zone area should be strictly prohibited when the process is in operation. It is also not recommended to place equipment in this area that could be damaged in such a situation.
If workers are required to regularly work near the flame arrester, a diverter to lead the explosion in a safe direction, may be used to separate workers and equipment. This panel should be placed at least 200 mm from the flame arrester surface.
Nederman has all the necessary professional knowledge and experience to select the right explosion protection solution to offer the best solutions for our customer´s process requirements. Contact our air filtration experts to find out more.