A cap assembly (102, 120, 130, 140, 150, 170, 190, 200, 230, 250, 280) for detecting leaks through a pressure valve (100, 202). According to various embodiments, the cap assembly comprises a body (104, 121, 141, 141, 152, 171, 191, 204, 232, 252) arranged in fluid communication with the valve; and a sensor (110, 110A, 110B, 174, 192, 214, 238, 262, 282), supported by the body to provide a human sensory cue indicating leakage of pressurized fluid from the valve in the closed position. In various embodiments, the sensory prompter may be a whistle that emits an audible sound, a light emitting device that emits visible light, and the like. In a further embodiment, the cap assembly body may be connected to the conduit (122) via a tether (106, 124, 154, 206, 254) and release pressure from the conduit in response to venting pressurized fluid when the valve transitions to the open position. pop up.