Where an explosible concentration of combustible dust can occur in a process, there prevails a risk of explosion. This risk can be mitigated by the selection and use of pertinent explosion protection measures. In this section, we cover equipment that is used for explosion isolation by mechanical means and does not need the triggered assistance of electrical detection (dynamic pressure, Infrared, or other sensors) to function. These are called passive explosion isolation devices or measures. Flame propagation can occur when there is a dust explosion in one vessel and the explosion runs through the interconnected ducting. A deflagration initiated in one process equipment can become a more serious and often uncontrolled event in other connected vessels.

CMC/Aircom’s explosion isolation flap valves (non-return valves)  are ATEX-certified EN 15089 – 16447 against the propagation of explosion in suction lines (pull flow).  They are made of carbon steel painted standard RAL 3020 or in stainless steel, AISI 304 or AISI 316, welded in all the unions, and the structure is reinforced to withstand high pressures and is supplied with a locking mechanism or with an anti-opening lock. The NRV combo valve is designed for organic dust applications, available in sizes DN100 to DN1200. It features a locking mechanism, pneumatic anti-opening locks, and counterweight with a lever to reduce pressure drop. The body materials are painted carbon steel or stainless steel. It is ATEX EN16447 certified and offers an optional capacitive sensor for dust accumulation detection. The valve can be re-armed manually or pneumatically.

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CMC/ Aircom’s heavy duty explosion islolation Safety Non-Return Valves for metal prevent explosion spread by instantly sealing off ductwork when blasts occur. Built rugged from steel to survive harsh conditions, these ATEX/EN16447 certified explosion barriers isolate ravages of fireballs and pressure waves. Tight seals and latching mechanisms stop flames and force from escaping past the locked barrier valves. Rated for extreme temperatures from -20°C to 60°C, they continue protecting facilities even when airspeeds within reach perilous levels.

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IsoDisc TM is a certified passive explosion Isolation device tested according to EN15089 that contains pressure and flames from dust explosions. The device can be used where the explosion direction is against the airflow direction. The IsoDisc, manufactured by IEP Technologies-Hoerbiger, is a versatile solution for clean “air service” applications. It is specifically designed for use in air intake ducts of milling operations such as hammer mills, as well as other applications like dryers. The IsoDisc is available in sizes ranging from DN50 to DN400, catering to different pipe connection diameters.

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Aircom’s safety non-return explosion isolation valves, are ATEX CERTIFIED EN 16447 against the propagation of explosion in suction lines. They are the sure solution to isolate the environments in case of explosion in the suction plants locking the explosive effect in the suction line.

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The BPF-M isolation valve from Brilex is used as a passive decoupling element in piping, where the dust concentration is above the “Lower Explosive Limit” (LEL), i.e. combustible dust/air mixtures of Zone 20 may be supported in this piping. Note: The BPFM is a discontinued product by Brilex. Refer to Aircom NRV Combo or IEP Technologies IsoFlap as an alternative. Under the same conditions, the isolation valve is also applicable for dust/air mixtures of Zones 21 and 22. The outer part of the isolation valve may be surrounded by a Zone 22. The isolation valve is approved as a type-tested safety system for both inorganic and organic types of dust explosion class ST1 according to guideline 94/9/EG.

The valve consists of a weighted, hinged, plate inside the main body. In normal operation, the plate is held open by the airflow through the valve. In the event of a dust explosion, the airflow is stalled and the plate will close. The plate will then be driven down hard on the valve seat by the explosion pressure. The RSK is a discontinued product by Brilex. Refer to Aircom SNR or NRV Combo or IEP Technologies IsoFlap as an alternative. The RSK valves can be used for dust explosion hazards in the ST1 and ST2 classes. The valve must be located horizontally in the inlet duct. The minimum distance between the vessel and the valve is as follows: 2m for sizes DN160 to DN400 or 3m for sizes DN450 to DN1000.

Brilex GmbH introduces the new Brilex REXS Explosion Diverter for safe, certified, and cost-effective explosion decoupling. The REXS features an advanced design in compliance to the DIN EN 16020 Explosion Diverter standard. It has low pressure drop for organic, inorganic, and metal dusts, and is suitable for duct diameters of up to 800mm. The REXS includes an enhanced, non-fragmenting, and certified Brilex DIV explosion vent. The Brilex DIV explosion vent is suitable for Kst values up to 200 bar.m/s and is also applicable for metal dust, duct lengths of up to 23 meters, and a maximum reduced explosion pressure (Pred,max) from 0.3 to 0.8 bar.

Thorwesten Vent – Type STT – Explosion Diverter, the standard version is self-reclosing. A simple additional device makes the STT diverter into a non-self-reclosing explosion diverter that can be reclosed manually.

Type DES explosion diverter, the standard version remains open to be reclosed manually. A simple additional device provides the feature of self-reclosing. This explosion diverter is used at the inlet to dust collector to prevent explosion pressure and flames from propagating back to the factory.

The IEP Technologies range of passive isolation flap valves are low-cost and reliable explosion isolation solutions that mitigate explosion propagation risks to upstream equipment. These passive isolation solutions are effective, self-actuating devices providing inlet explosion isolation to protected vessels handling combustible dust such as dust collectors, cyclones, and other process equipment. Whether the best explosion protection solution is suppression, venting, or isolation, IEP Technologies offers the right products to meet your needs. Our system components undergo rigorous third-party testing to receive the approvals required by, for example, ATEX and NFPA. As each explosion protection threat is unique, we offer different types of explosion detectors, controls, and suppressors to tailor the protection to each individual application.

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VENTEX ESI are explosion isolation systems after EN15089:2009D. Explosion isolation with VENTEX valves is used in systems in which combustible dust, gases, or hybrid mixes are processed. The Ventex valves can be utilized in a wide range of application areas, including silos, mills, drying chambers, separators, dust collectors, and extraction systems. It finds great utility in various industries such as the food industry, pharmaceutical industry, chemical/petrochemical industry, research laboratories, and wood processing. Additionally, it is suitable for many other situations involving the handling of combustible dust.

The next generation of Ventex explosion protection valves features a flow velocity of at least 30 m/s, thus ensuring an even higher level of process reliability and flexibility. The valve can be placed directly upstream or downstream of pipe bends in the pipeline; double pipe bends or a combination of pipe bends in different directions is also not a problem. The next generation Ventex explosion protection valve offers improved process reliability and flexibility with a flow velocity of at least 30 m/s. It eliminates the need for a straight pipe section and allows for installation directly after pipe bends. The extended installation distance for organic dust explosions and certification for metallic dust explosions up to DN400 provide increased flexibility. With better pressure drop values, a new DN250 size, and simplified maintenance using plug-in gaskets, the valve brings enhanced performance. It features fully integrated mechanics, an aerodynamic axis mount, high temperature resistance, and customizable surface treatment options for optimal functionality.

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Passive protection against explosions. In “single acting” ESI-E and “double-acting” ESI-D versions, the VENTEX Type 6 provides explosion protection in one ore both flow directions without requiring external energy. The product line offers two variations: the E model, which is single-acting without external energy or passive, and the D model, which is double-acting without external energy or passive. These models are designed to handle various types of hazardous atmospheres, including gas, dust, and hybrid mixtures. The maximum air speed allowed in the direction of an explosion is 20m/s, with an optional 25m/s, while the maximum air speed against the direction of an explosion is 35m/s. 

The VENTEX ESI-C Type 6 passive explosion protection valve is a check valve that does not require external energy. Its specific functionality means that it can provide explosion protection against the direction of flow. The C model check valve is for hazardous atmospheres. It operates without external energy, has low response pressure and pressure loss, and requires minimal maintenance. It can be installed horizontally or vertically and offers fast recovery after an explosion. Available in sizes DN100 to DN600, it ensures reliable and clean operation with no soiling.