Flame arrester
Flame arresters are fittings which, as so-called "autonomous protection systems" , are intended to prevent an explosion from spreading to other parts of the system. A distinction is made between static and dynamic flame barriers. They must be installed in particular if explosive gas-air mixtures can form and an explosion can spread in containers or system parts that are not designed to be explosion-proof (explosion-pressure-proof or explosion-pressure shock-proof). Systems are explosion-pressure-resistant if they can withstand the maximum explosion pressure occurring in the event of an internal explosion without deforming the affected systems (components) and these are still technically tight afterwards. Systems that withstand the maximum explosion pressure (possibly with plastic deformation) and then remain technically tight using the material ductility are referred to as explosion pressure shock resistant. These devices are intended to prevent an explosion from being transmitted to other downstream system parts or to the outside by means of explosion protection decoupling. These are structural explosion protection components which, as a tertiary protection measure, limit the effects of an explosion to a controllable level. Flame arresters are fittings for explosion protection . They are also known as flame arresters or kito . Kito is the abbreviation for gravel pot, this is the original design of the flame arrester.
Flame arresters are i. d. Usually defined via the European standard EN ISO 16852: 2016, which was adopted as a German standard. The EN ISO 16852: 2016 replaced the earlier EN 12874: 2001.
The mode of operation is based on the fact that a flame front is cooled by built-in components (e.g. rolled up sieve plates, gravel bed) to such an extent that a flame cannot spread further behind the flame arrester. One distinguishes between:
The type of flame arrester used depends in practice on the medium, the distance to the ignition source and the application (pipe fuse, end fuse).
Definitions
Deflagration protection
The deflagration protection is used to prevent the spread of an explosion in closed systems that are virtually pressureless by extinguishing the flame in the protection. For this purpose, tape securing devices with narrow gaps and earlier gravel fillings are used. Deflagration arresters must be installed close to the ignition point. Upstream and downstream straight pipelines must not exceed a ratio of diameter to length (D / L) of 1:50.
End fuses (on tanks or vent lines) are deflagration fuses , as they are installed at the point where the ignition occurs at the connection between the ventilation line and the atmosphere. End locks are often endurance resistant, i. H. A prolonged fire does not impair the safety equipment due to the heating of the valve. End fuses that are not endurance burning can be equipped with a temperature sensor, which automatically initiates the interruption of the gas flow, e.g. B. by closing a valve or switching off a pump. Type tests according to ATEX Directive 2014/34 / EU and EN ISO 16852 are valid for an operating pressure of maximum 1.1 bar (absolute) and a maximum operating temperature of 60 ° C. The gap width of the strap securing device is determined by the explosive substance used; the determining factor is the explosion group .
Detonation protection
The detonation protection extinguishes the flames in pipes after a gas detonation and prevents the spread of an afterburn. A stable detonation develops in a pipeline with a D / L ratio greater than 1: 120. In the case of D / L ratios 1:50 to 1: 120, unstable detonations develop , which should be avoided as far as possible when installing detonation safeguards. A detonation is characterized by flame velocities in the supersonic range (approx. 1600 to 2000 m / s). The spread of flames due to a detonation in the more distant parts of the system can be prevented by detonation safety devices.
Measures in the event of an endurance fire
Flame arresters are offered as endurance-proof and non-endurance-proof versions. The flame effect heats the fuse and if it is exposed to the flame for a longer period of time, the flame can ignite in the non-endurance burning version. In these cases, a temperature sensor must be installed on the side on which ignition is expected, and the material flow must be interrupted when triggered. This can be done by closing a valve or switching off a fan. Flame arresters equipped with temperature sensors on both sides of the tape fuse are suitable for bidirectional use.
application areas
- Ventilation and ventilation of tank farms
- Landfill and biogas plants
- Sewage gas utilization
- Exhaust air incinerators
- Mine gas utilization
- Chemical industry with the use of solvents
- Guidelines
- EU directive 2014/34 / EU ("ATEX 114") Explosion protection products or explosion protection internal market directive according to Art. 114 TFEU (ex. 94/9 / EC)
- EU directive 1999/92 / EG ("ATEX 153") Explosion protection operator directive (social standard according to Art. 153 TFEU)
- Norms
- EN ISO 16852: 2016
- EN 1127-1: 2019-10
- Designs
- eccentric
- concentric
- right angled
- End of line
- 30 ° conicity
- 2 × DN larger filter element
Other types of flame arresters:
- Water dives,
- Liquid closures (with liquid product as a barrier; construction like a siphon),
- High-speed valves (so-called dynamic flame arresters),
During immersion, a potentially explosive gas mixture is passed through water at a safe minimum height. The water reserve prevents an explosion from spreading backwards.
Rotary locks and extinguishing agent barriers are not considered as flame arresters, as they are only intended for use with dust.
literature
- Ralph-Harry Klaer (Ed.): Practical manual for industrial fittings 2003. Vulkan Verlag GmbH, Essen 2003, ISBN 3-8027-2729-0 .
- Mario Kräft (Hrsg.): Explosion protection with flame barriers 2007. Verlag Joachim Mackensen, Berlin 2007, ISBN 978-3-926535-53-5 .
- Klaus Ridder, Jörg Holzhäuser: ADN 2017. 9th edition, Verlag ecomed Sicherheit, Landsberg am Lech 2016, ISBN 978-3-609-69748-2 .
- Helmut Schaefer (Hrsg.): VDI-Lexikon Energietechnik . Springer-Verlag Berlin Heidelberg GmbH, Berlin Heidelberg 1994, ISBN 978-3-642-95749-9 .
- Henrikus Steen (ed.): Manual of explosion protection. Wiley-VCH, Weinheim 2000, ISBN 978-3-5272-9848-8 .
Web links
- Flame arresters and valves. (PDF) Huckauf Engineers, KITO, 2018.
- Graphic symbols for flame arresters. (PDF) Protego Braunschweig Flame Filter, May 26, 2016.
- Technical rules for operational safety Dangerous explosive atmosphere - structural explosion protection measures which limit the effects of an explosion to a harmless level. (PDF) Asecos, February 2012(TRBS 2152, part 4).
- EC type-examination certificates for static flame arresters with flame arresters made from wound tapes. (PDF) PTB , BAM .
- Use of flame arresters at filling stations for gasoline and mixtures of ethanol and gasoline up to and including E85. (PDF) Bruno Rapp AG.