A re-configurable pressure regulator for breathing apparatus having a valve housing with a connector at a first and a second end. A pressurized source of breathable gas is connected to either end and a removable blanking plug is connected to the other end of the housing. A double acting valve within the housing selectively opens a first or second opening in the housing, depending on which end the source of breathable gas is connected, which opening forms the inlet and outlet from the housing.