The influence of the number of explosion vents for the same total vent area was experimentally investigated using free venting using a 460mm long 162mm diameter (L/D = 2.8 0.01 m3) cylindrical vented vessel with end ignition opposite the vent. Two vent coefficients ( Kv = V2/3/Av), of 10.9 and 5.4 were investigated for a single vent and for a 16 hole vent (Multiple vents) for each Kv. Different mixtures of methane-air and ethylene-air, worst case concentrations of 10% and 7.5% respectively, were used in order to study the influence of mixture reactivity. It was shown that the multiple hole vents generated a higher P2 internal overpressure as a result increase in the area of the flame upstream of the vent. The flame had to spread between 16 vents, compared to the single hole vent in line with the ignition where the flame accelerated towards the vent with little radial flame spread and split. However, the single vent was shown to give a greater external overpressure and higher flame speeds downstream of the vent due to higher turbulence length scale and hence greater turbulent burning velocity. It was concluded that the single vent increased the peak pressure and external explosion flame speed when compared to the multiple vents significantly due to difference in turbulent length scales. Consequently, the use of multiple vents helps to reduce the overpressure for low burst pressures vents.