Water out alarm
AssigneeFisher & Paykel Healthcare Limited
InventorsDean Antony Barker, Jack Che-Wei Hsu, Jae Chul Han
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Abstract
The present invention provides for an improved method of determining a water out condition in a humidified gases supply apparatus. The method includes a two step process including a primary determination of a water out condition and a secondary determination of a water out condition. This primary determination is made during observation of the normal operation of the apparatus. During the secondary determination the method takes temporary control over the humidifying part of the apparatus. The secondary determination confirms or contradicts the primary determination.
Claims20
An apparatus for preparing a flow of gases including:
- a heater for heating a reservoir,
- a temperature sensor in thermal communication with the heater to read the temperature of the heater,
- a controller adapted to apply power from a power supply to the heater, the controller including a control method comprising:
- monitoring system conditions during use of the apparatus,
- determining a possible absence of water in the reservoir from the monitored system conditions,
- following a determination of a possible absence of water, apply an amount of power from the power supply to the heater, the amount of power being:
- an increase in the supplied power,
- a maximum power from the power supply to the heater,
- a predetermined amount of power from the power supply to the heater;
- or
- an amount of power to the heater that would elevate the heater temperature in the absence of water, to a temperature that exceeds any temperature that the heater temperature would reach with water present in the reservoir,
- monitoring an output of the temperature sensor, and
- reducing the power supplied from the power supply to the heater if the monitored temperature sensor output indicates an absence of water in the reservoir.
An apparatus for preparing a flow of gases including:
- a humidifier including a reservoir and a heater for heating the reservoir,
- a temperature sensor in thermal communication with the heater to read the temperature of the heater,
- a controller adapted to apply power from a power supply to the heater, the controller including a control method comprising:
- monitor system conditions during use of the apparatus,
- determine a possible absence of water in the reservoir from the monitored system conditions,
- following a determination of a possible absence of water,
- applying a maximum available power from the power supply to the heater,
- monitoring an output of the temperature sensor,
- determining a water out condition if the output of the temperature sensor exceeds a predetermined threshold for a predetermined period of time,
- subsequently reducing the power supplied from the power supply to the heater, and
- providing an output indicating the water out condition.
Dependencies are inferred from the claim text.