Change characteristics of gas explosion venting pressure inside spherical vessel with a small caliber

With air-methane premixed gas as medium, a series of experiments were conducted under both constrained and unconstrained conditions of caliber to study the varying characteristics of explosion venting pressure in 22L spherical container with different dimensionless pressure relief ratios. The results show that, in constrained circumstances and with broken membrane pressure unchanged, both the rising rate of maximum explosion venting pressure and the maximum vented pressure inside the spherical container increase with decrement of dimensionless pressure relief ratio. If the dimensionless pressure relief ratio is more than a certain value, the vented explosion is balanced vented explosion; if not, it is non-balanced vented explosion. Under constrained condition, when dimensionless pressure relief ratio is more than 0.009 and less than 0.025, vented explosion has remarkable effect and the pressure decreases obviously. When dimensionless pressure relief ratio is more than 0.00169 and less than 0.009, the maximum venting pressure is close to the pressure of hermetic explosion and the pressure does not decrease well. When dimensionless pressure relief ratio is less than 0.00169, the maximum explosion venting pressure slightly exceeds the maximum explosion pressure in closed vessel. Under the unconstrained condition, the maximum explosion venting pressure inside spherical container with different dimensionless pressure relief ratios is lower than the maximum explosion pressure in closed vessel. The results provide scientific basis for the safety design of vented explosion in spherical container in the industrial production.