Abstract: Active explosion suppression test of methane/air mixtures was carried out in a 100 L closed chamber through an ultrafast trigging of the trialmanufactured suppressor,in which the superfine ABC powder was prefilled and temporary pressurized by the activation of solid nitrogen generator at proper time after ignition,intended to investigate the influence of key parameters on the efficiency of explosion suppression.Results show that the flame propagation could be quenched completely if the gas generator was triggered within critical time,in which case all of the flame profile were covered by 40 g discharged superfine ABC cloud,whereas the explosion intensity could not be suppressed when the trigger time exceeds 55 ms after ignition.Under the trigger time of 55 ms,the explosion flame propagation can be extinguished only when the discharging amount of explosion suppression medium is increased to 60 g.It was verified that no inhibition effect on explosion was presented when the discharge of superfine ABC powder was below the critical mass,whereas further improvement of explosion suppression effect was not significant in case of the injection of explosion suppression medium was above this threshold level.In addition,as a necessary carrier for ultrafine ABC powder discharge,the injection of nitrogen into the chamber of 100 L volume significantly strengthened flame propagation,this deficiency can be overcome expectedly by appropriate redundancy discharge of the ultrafine ABC powder.