A flammable gas diluter includes a dilution vessel having an outer envelope defining a longitudinal flow passage from an inlet to an outlet; at least one air inlet assembly for directing a flow of air into the inlet of the dilution vessel; a flammable gas inlet arrangement located towards an inlet end of the dilution vessel; two gas flow generators configured to pump a flow of air into the air inlet assembly, the two gas flow generators being located upstream of the flammable gas inlet arrangement; and two dampers, each of the dampers being mounted between a corresponding gas flow generator and the dilution vessel. Control circuitry is configured to open a damper during an operational mode of the corresponding gas flow generator and to close the damper when the corresponding gas flow generator is stopped in standby mode.