Deflagration and detonation arrester

This concept book is intended for nse by chemical engineers and other technical personnel involved in the design, operation, and maintenance of facilities and eqnipment where deflagration and detonation arresters (DBAs) may be reqnired. These people are nsnally technically competent individnals who are aware of, bnt not experts in, combnstion phenomena. The facilities where snch devices may be needed inclnde chemical plants, petrochemical plants, petrolenm refineries, pharmacentical plants, specialty chemical plants, storage tank farms, loading and nnloading facilities, and pipelines. 

DDA Deflagration and detonation arresters or deflagration and detonation flame arresters. 

Decomposition Flame Arresters Above certain minimum pipe diameters, temperatures, and pressures, some gases may propagate decomposition flames in the absence of oxidant. Special in-line arresters have been developed (Fig. 26-27). Both deflagration and detonation flames of acetylene have been arrested by hydrauhc valve arresters, packed beds (which can be additionally water-wetted), and arrays of parallel sintered metal elements. Information on hydraulic and packed-bed arresters can be found in the Compressed Gas Association Pamphlet G1.3, Acetylene Transmission for Chemical Synthesis. Special arresters have also been used for ethylene in 1000- to 1500-psi transmission lines and for ethylene oxide in process units. Since ethylene is not known to detonate in the absence of oxidant, these arresters were designed for in-line deflagration application. 

This book makes reference to flame arresters, deflagration flame arresters, and detonation flame arresters. Flame arresters is the generic term for both deflagration and detonation flame arresters. Deflagration flame arresters are nsed when a flame only propagates at snbsonic velocity, whereas detonation arresters are nsed when a flame can propagate at all velocities inclnding snpersonic velocities. 

This book covers many aspects of DBA design, selection, specification, installadon, and maintenance. It explains how varions types of flame arresters differ, how they are constrncted, and how they work, ft also describes when a flame arrester is an effective solntion for mitigation of deflagrations and detonations, and other means of protection (e.g., oxidant concentration rednction) that may be nsed. It also briefly covers some aspects of dnst deflagration protection. 

In Germany, deflagration and detonation flame arresters are tested and approved by the German Federal Physical-Technical Institnte (PTB) in Brannschweig and the German Federal Institnte for Material Research and Testing (BAM) in Berlin. However, once the new Enropean Committee for Standardization (CEN) standard is approved, it will supersede the PTB and BAM procedures. 

The International Maritime Organization (IMO) published a standard in 1984 for the design, testing and locating of deflagration and detonation flame arresters and high velocity vent valves for cargo tanks in tanker ships (IMO 1984). This was amended in 1988 and reissued as Revision I (IMO 1988). A new revised standard was issued in 1994 (IMO 1994). 

This chapter presents an overview of the varions practices nsed in the chemical process indnstries to prevent and protect against deflagrations and detonations. It inclndes an introdnction to deflagration and detonation flame arresters and also other methods that can he nsed when flame arresters are not practical or are too expensive. 

In almost all cases, if a flame arrester is placed in-line rather than at (or close to) the open end of a vent pipe, a detonation flame arrester is needed. Detonation flame arresters mnst be able to stop both deflagrations and detonations. They require extensive testing and mandatory testing protocols may apply. 

Dry type deflagration and detonation flame arresters have an internal arrester element (sometimes called a matrix) that quenches the flame and cools the products of combustion. A great number of arrester elements have been developed and used. The most common types currently available are as follows ... 

Other types of deflagration and detonation flame arresters that do not contain an arrester element (matrix) have been used snccessfnlly in various applications where conventional dry type arresters were not suitable or were very expensive. Among these are ... 

Crimped metal ribbon flame arresters are applicable for both deflagrations and detonations. They are especially used for detonations, since the apertures can be made very small, which is necessary to stop a detonation. 

Expanded metal cartridge flame arresters are available for deflagration and detonation applications and are designed for bidirectional flow. 

Snccessful full-scale tests on quenching of deflagrations and detonations using expanded metal cartridge flame arresters were performed to USCG standards on Group C and D gases by Westech Industrial Ltd. (Lapp 1992, Lapp and Vickers 1992). 

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