An emergency evacuation slide system includes a control valve having a normally-open vent that closes after a predetermined period of time calculated to vent excess inflation gas produced by the gas generator. In operation, in the event of an aircraft emergency exit door being opened in the "armed" condition, the primary valve member of the control valve is opened allowing inflation gas to flow into the valve chamber. A portion of the gas entering the chamber is vented through the normally-open vent. After a predetermined period of time calculated to be sufficient to vent the excess inflation gas, the normally-open valve is closed to divert 100% of the remaining inflation gas into the evacuation slide.