Abstract: A fault protection circuit for a respiratory conduit heater element in a respirator humidification system is disclosed. The circuit includes a spark detector as well as overcurrent detector. Several variations are included for the spark detector including a two winding transformer, a centre tapped two winding transformer), and a high pass filtered inductor. A semiconductor switching configuration is also disclosed. Once the protection circuit detects a change in current over a certain level, or the average level raises above a threshold, then the current in the heater element is interrupted for a preset period.

Abstract: A method and apparatus are described for sensing the absolute humidity of gases where the relative humidity of gases are measured, the humidity transducer is heated, the resulting temperature measured and the absolute humidity calculated (based on the power to heat said transducer, the temperature of said transducer and the relative humidity).

Abstract: A flow probe for use in a humidification system is disclosed. The flow probe is adapted to be positioned in a humidified gases flow (for example oxygen or anaesthetic gases) such as that which is provided to a patient in a hospital environment. The flow probe is designed to provide both temperature and flow rate sensing of the gases flow by incorporating two sensors (preferably thermistors) and the shape and alignment of the probe enables accurate readings by reducing the occurrence of condensation on the sensors.

Abstract: A humidifier and humidity sensor is disclosed for use with a breathing assistance apparatus. The humidity sensor preferably includes means to sense absolute humidity, relative humidity and/or temperature at both the patient end and humidifier end. The humidifier may also include provision to both control independently the humidity and temperature of the gases. Further, a chamber manifold is disclosed to facilitate easy connection of the humidifier to various outlets, inlets and sensors. A heated conduit is described which provides a more effective temperature profile along its length.

Abstract: A flow probe for use in a humidification system is disclosed. The flow probe is adapted to be positioned in a humidified gases flow (for example oxygen or anesthetic gases) such as that which is provided to a patient in a hospital environment. The flow probe is designed to provide both temperature and flow rate sensing of the gases flow by incorporating two sensors (preferably thermistors) and the shape and alignment of the probe enables accurate readings by reducing the occurrence of condensation on the sensors.