An an inflator for the inflation of inflatable articles such as life vests and the like, such inflator being operated automatically upon being subjected to water as upon the ditching or parachuting of an aviator wearing a life vest provided with such inflator. In the preferred embodiment of the inflator disclosed, the automatic operating portion of it is embodied as an attachment to a known manually operated inflator, the resulting inflator being capable of operation both manually and automatically. The automatic operating portion of the inflator incorporates a releasable blocking device which holds an actuator pin operated by a coil compression spring in cocked condition until the releasable blocking device releases the actuator pin, which thereafter thrusts a piercing pin against and through the sealing diaphragm of a gas-containing capsule. The releasable blocking device is provided with a water destructible element which retains the releasable blocking device in actuator pin cocking position until the water destructible element is submerged in water entering through specially designed apertures. The automatic inflator further includes a color coded indicatior system for indicating the state of the inflator, ready and armed or dispensed and in need of reloading.