Supports for Static and Dynamic Forces

Nichols (1999) describes a nnmber of reaction forces that are generated dnring deflagrations and detonations in piping systems snch as  

A radial force on the pipe wall ahead of the deflagration wave. There is a varying pressnre between the aconstic wave and the flame front where the pressnre bnilds from near atmospheric pressnre, Pi (step change at the wave front) to eight times Pi (or higher) at the flame front. The pressnre ratios depend on the flame acceleration. There is no snch effect with a detonation. 

A radial force on the pipe watt behind the flame front. For a closed pipe, this remains constant (at abont STi) everywhere for a deflagration, bnt decays from abont 20Ti to STi behind the detonation over most of the pipe length. 

Longitndinal ont-of-balance forces. For a Z-confignration pipe layont there is a steady force between the two bends generated by the pressnre difference in the gas while the pressnre front moves between the two bends. This gives a longer dnration to the force which can approach the resonant freqnency of the pipe. 

Detonation flame arresters and associated piping mnst be able to withstand the effects of explosion transients that inclnde the pressnre or pres-snre-related force, the specific impulse (integral of the dme versus overpressure) or net impulse (upstream minns downstream impulse) highspeed gas momentnm transfer and flnx, and temperatnre-, heat-, and dier-mal-flnx related loads (White and Oswald 1992). Wliite and Oswald con- 

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