Flame Arresters (or ‘flame arrestors’) are designed to allow the flow of gases, liquids, etc. and to prevent flame transmission.
PROTEGO® Flame Arresters are composed of individual FLAMEFILTER® (flame arrester discs), spacers, and a casing. The FLAMEFILTER® is made of wound, corrugated metal strips. The principle of flame quenching in small gaps is applied in PROTEGO® end-of-line flame arresters and PROTEGO® in-line flame arresters.
When a mixture ignites in a gap between two walls, the flame spreads towards the non-combusted mixture. The expansion in volume of the combusted mixture pre-compresses the non-combusted mixture and accelerates the flame. By heat dissipation in the boundary layer “s”, transferring it to the large surface of the gap length compared to the gap width “D”, and by cooling down the product below its ignition temperature, the flame is extinguished.
The gap width and the gap length of the flame arrester disc determines its extinguishing ability. The narrower and longer the gap, the greater the extinguishing effectiveness. The wider and shorter the gap, the lower the pressure loss. Experiments can determine the optimum solution between the two conditions.
Different gases have different flame propagation capacities and are categorized into explosion groups corresponding to their hazard level. The standard for this is the MESG = Maximum Experimental Safe Gap, a characteristic number measured in the laboratory for the flame propagation ability of the product.
The MESG, or standard gap width, is the largest gap width between the two parts of the interior chamber of a test setup which, when the internal gas mixture is ignited and under specified conditions, prevents ignition of the external gas mixture through a 25 mm long gap, for all concentrations of the tested gas or vapor in air.
The MESG is a property of the respective gas mixture [EN 1127-1]. NOTE: The test setup and methods are specified in EN 60079-20-1. The most explosive composition is close to the stoichiometric mixture of the gas/vapor-air mixture.
|Explosion group||Max. Experimental Safe Gap (mm)||NEC||Reference Substances for testing flame arrester|
The table shows the categorization of substances into the respective explosion group according to their MESG (IEC 79-1, EN ISO 16852).
This design prevents the FLAMEFILTER® discs from being damaged or misaligned during assembly or maintenance.
These PROTEGO® Flame Arresters are particularly suited to applications where more frequent maintenance of the FLAMEFILTER® is required (e.g., where polymerization or crystallization result in heavy contamination) or for IIC applications.
After installation, PROTEGO® units can be retrofitted at any time.