Abstract: In a breathing apparatus and a method for the operation thereof, a gas monitor monitors at least one gas and includes a pump that controls a sidestream flow from a patient circuit to the gas monitor via a sampling line having a first end connectable to the gas monitor and a second end connectable to the patient circuit. At least one pressure sensor measures a pressure at the sidestream gas monitor and provides a first pressure signal indicative of the measured pressure. A processor determines if a leakage is occurring in the sampling line based on the pressure signal.

Abstract: The disclosure relates to detection of leakage in a sampling line of a breathing apparatus, which comprises a gas monitor (102) for monitoring at least one gas, including a pump (106) for controlling a sidestream flow to the gas monitor (102), connectable to a mainstream of a patient circuit (108); a sampling line (110) for the sidestream flow, having a first end (112) being connectable to the gas monitor (102) and a second end (114) being connectable to the patient circuit (108); and at least a first pressure sensor (118) for measuring a pressure at the sidestream gas monitor (102), in operation providing a first pressure signal for the pressure; and a processing unit (120) operative to determine if a leakage of the sampling line (110) is occurring based on at least the first pressure signal.

Abstract: A flow meter arrangement has a venturi-type flow meter having a tubular flow channel for conveying a gas flow to be measured and in which there is provided a constriction. The arrangement further has a hot wire flow meter having a sensing element located within the flow channel and a measurement system that receives an output from the venturi-type flow meter and an output from the hot wire flow meter, and that determines a gas flow rate therefrom.

Abstract: A flow meter arrangement has a venturi-type flow meter having a tubular flow channel for conveying a gas flow to be measured and in which there is provided a constriction. The arrangement further has a hot wire flow meter having a sensing element located within the flow channel and a measurement system that receives an output from the venturi-type flow meter and an output from the hot wire flow meter, and that determines a gas flow rate therefrom.

Abstract: A hot wire gas flow rate sensor having a bridge circuit with a sensing resistor avoids saturation of the signal processing circuitry at high gas flow rates by increasing a bias signal to a differential amplifier in the signal processing circuitry in a step-like manner as the flow rate responsive signal to the differential amplifier from the sensing resistor increases. The differential input signal to the amplifier is thus maintained at a level that avoids saturation of the amplifier. Appropriate scaling is provided to the output circuitry of the sensor in accordance with changes in the bias signal so that the sensor output correctly indicates gas flow rates. Compensation is provided for changes in gas composition and when the sensing resistor is changed by determining the voltage drop across a first sensing resistor with a gas of known composition at a zero gas flow condition. The voltage drop across a second sensing resistor at the zero gas flow condition for the gas is also determined.