Abstract: The present invention provides a breathing apparatus and a controller for a breathing apparatus. The controller is configured to receive a first output signal from a pressure sensor in the breathing apparatus, wherein the first output signal is indicative of variations in a total gas pressure within the breathing apparatus. The controller is further configured to determine, using the first output signal, an oxygen consumption rate of a user of the breathing apparatus. This may enable the controller to determine the user's oxygen consumption rate, without having to rely on an oxygen sensor. The breathing apparatus may be a rebreather, which is used for underwater diving.

Abstract: A controller for controlling a breathing apparatus that comprises a plurality of oxygen sensors, each for sensing an oxygen content of a gas in the breathing apparatus, the controller being configured to control the operation of the breathing apparatus based on the output of one or more of the oxygen sensors and additional information relating to the operation of the breathing apparatus. Also a breathing apparatus comprising the controller and the plurality of oxygen sensors.

Abstract: A controller for controlling a breathing apparatus that comprises a plurality of oxygen sensors, each for sensing an oxygen content of a gas in the breathing apparatus, the controller being configured to control the operation of the breathing apparatus based on the output of one or more of the oxygen sensors and additional information relating to the operation of the breathing apparatus. Also a breathing apparatus comprising the controller and the plurality of oxygen sensors.