Explosion calculations Relief sizing

Explosion calculations, 499-504 Estimating destruction, 501 Overpressure, 502 Pressure piling, 501, 504 Relief sizing, 505 Scaled distance, 502, 503 Schock from velocity, 503 TNT equivalent, 499-504 Explosion characteristics of dusts, 515 Explosion suppression, 518 Explosion venting, gases/vapors, 504 Bleves, 504 Explosions, 482 Blast pressure. 496 Combustion, 482 Confined, 482 Damage, 498-501 Deflagration, 482 Detonation, 483... 

Rupture disks are used for the same purpose as safety valves and, in addition, serve to relieve internal explosions in many applications. If the pressure rise can be anticipated, then the volume change corresponding to this change can be calculated by simple gas laws, and the capacity of the disk at the relieving pressure is knowm. The system must be examined and the possible causes of overpressure and their respective relief capacities identified before a reliable size can be determined. See Figure 7-14. 

Side note A relief valve is an instrument on the top of the reactor tl releases the pressure and contents of the reactor before temperature a pressure builds up to runaway and explosive conditions. The safety rel valve is similar to the rupture disk in that once the reactor pressure excer the set pressure the contents are allowed to flow out through the vent, the pressure falls below the vapor pressure of the reactor contents, the lau heat of vaporization will cool the reactor. The self-heating rate may be us directly to calculate the vent size necessary to release all the contents of 1 reactor. The necessary vent area, Av is given by the equation for a va[ system and two-phase flashing flow. 

An explosion relief vent must be carefully sized to ensure that it will effectively relieve the potential explosion. Factors influencing the calculation include the material explosion pressure characteristics, the plant strength, vent position and the influence of ducting if required. Consideration must also be given to the plant configuration and the availability of an area into which the explosion can safely be discharged. 

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