Dual mode breathing apparatus

A breathing apparatus includes a canister containing pressurized breathing gas, a regulator having an inlet connected to the canister, an outlet for providing breathing gas to a user, and a valve configured for controlling flow of breathing gas between the inlet and the outlet. The face shell includes a first port for connection with an outlet of the regulator, a second port adapted to be connected to an air purification system, and an exhalation valve. A pneumatic pressure regulation assembly is operably connected to the exhalation valve and has a first pneumatic connection operably connected to a second pneumatic connection in the regulator. The pneumatic pressure regulation assembly is operable to regulate an internal face shell pressure for opening the exhalation valve based on whether breathing gas is delivered to the pneumatic pressure regulation assembly. An alignment mechanism is provided for aligning the regulator with the facepiece. 呼吸设备包括容纳加压呼吸气体的罐、具有连接到罐的入口的调节器、用于向用户提供呼吸气体的出口，以及被配置为用于控制入口与出口之间的呼吸气