Vent static burst pressure influences on explosion venting

The overpressure generated in a 10L cylindrical vented vessel with an L/D of 2.8 was investigated, with end ignition opposite the vent, as a function of the vent static burst pressure, Pstat, from 35 to 450mb. Three different Kv (V2/3/Av) of 3.6, 7.2 and 21.7 were investigated for 10% methane-air and 7.5% ethylene-air. It was shown that the dynamic burst pressure, Pburst, was higher than Pstat with a proportionality constant of 1.37. For 10% methaneair Pburst was the controlling peak pressure for K <~8. This was contrary to the assumption that Pred > Pburst in the literature and in EU and US standards. For higher Kv the overpressure due to flow through the vent, Pfv, was the dominant overpressure and the static burst pressure was not additive to the external overpressure. Literature measurements of the influence of Pstat at low Kv was shown to support the present finding and it is recommended that the influence of Pstat in gas venting standards is revised.