For process equipment mounted outside or close to an outside wall, explosion relief venting is a viable protection method. However, in order to protect the upstream equipment, it is vital that the protection method includes a means to mitigate propagation of flame and burning materials back upstream. This can be achieved by either using an active isolation system (chemical or mechanical), or by using a passive isolation valve. The passive explosion isolation valve is a self-actuating device, which provides a mechanical barrier to mitigate the propagation of flame and burning materials to upstream equipment. The passive isolation valve provides features unique to this style of valve, including an Accumulation Sensor, Wear Sensor and Interface Panel.