A pneumatic air valve core serves as a check valve during inflation of articles such as sphygmomanometer cuffs and as a flow control valve when the pressure is released. The core is mounted in a valve housing, which is connected by screw threads to an inlet housing. An adjusting screw is mounted in a threaded bore extending through the inlet housing, and the screw contacts the stem of the valve core. The adjusting screw depresses the stem of the valve core and holds the valve core open when the housings are screwed closer together, but allows the core to function as a check valve when the housing are screwed farther apart. A vent hole extends through one of the housings and communicates with the valve core. A control sleeve, attached to one of the housings, lets air flow through the vent hole when the housings are screwed closer together, but shuts off the flow through the vent when the housings are screwed farther apart. Thus, when the housings are screwed apart air supplied to the inlet housing passes through the valve core to the article being inflated. The valve core serves as a check valve until the housing are screwed closer together, at which time the pressure is relieved through the valve core and vent hole.