Abstract: An integral pressure sensor for a pressurized vessel, including a housing, a core element, a seal and a spring. This combination is disposed on the interior of the pressurized vessel. The core element is preferably a magnetic element or a steel ball which moves in the housing under the effect of the vessel pressure, and the chamber or housing pressure. The spring and seal combination together with the core element, function to trap a specified volume of the pressurized medium in the chamber when the vessel is initially pressurized. When the pressurized vessel leaks, the trapped pressure within the chamber exceeds the vessel pressure thereby causing the core element to move. The position or presence of the core element is detected using a detecting device such as a Hall-effect device or another magnetic device.