System and method for determining leak in respiratory flow therapy systems

A respiratory apparatus that is configured to provide a flow of gases to a user for respiratory therapy comprising:

• a flow generator that is operable to generate a flow of gases, wherein the flow generator is motor-driven;
• a flow path for the flow of gases through the respiratory apparatus to a gases outlet of the respiratory apparatus;
• a humidifier that is operable to heat and humidify the flow of gases, the humidifier comprising a removable humidification chamber in the flow path;
• a pressure sensor configured to generate a pressure variable representing a sensed pressure characteristic of the flow of gases in the flow path;
• and
• a controller that is operatively connected to the flow generator and operable to control a flow rate of the flow of gases by controlling a motor speed of the flow generator, wherein the controller is configured during operation to execute a leak detection process for detecting leaks in the flow path by:
• initiating a first-stage leak evaluation comprising comparing the pressure variable to a first leak threshold, the first leak threshold representing a possible leak condition;
• and
• initiating a second-stage leak evaluation if the pressure variable is below the first leak threshold thereby indicating a possible leak, the second-stage leak evaluation comprising:
• increasing the motor speed of the flow generator from a current motor speed to a higher motor speed,
• comparing a new pressure variable at the higher motor speed to the first leak threshold and a second leak threshold, the second leak threshold representing a definite leak condition, and then:
• generating a leak alarm and exiting the second-stage leak evaluation if the new pressure variable is below the second leak threshold thereby confirming the possible leak as a definite leak;
• or
• exiting the second-stage leak evaluation without generating an alarm if the new pressure variable is above the first leak threshold and second leak threshold thereby resolving the possible leak as no leak;
• or
• repeating the second-stage leak evaluation at a further higher motor speed or speeds until the possible leak is confirmed as a leak or resolved as no leak.