Method for determining a flow rate, flow sensor, and measuring system comprising a flow sensor

A method for determining a flow rate of a fluid through a flow sensor (15) having a measurement channel (19), in particular a flow sensor for testing a respirator, the method comprising at least the following steps:

• a. providing a fluid in the measurement channel (19) of the flow sensor (15), wherein three resistive elements (20a-20c) are present in the measurement channel (19);
• b. detecting at least one first differential pressure in the measurement channel (19), wherein the at least one first differential pressure is present in a first differential pressure range (22) in the measurement channel (19), and wherein the first differential pressure is detected over the second resistance element (20b), or is detected over the second and third resistance elements (20b, 20c);
• c. detecting at least one second differential pressure in the measurement channel (19), wherein the at least one second differential pressure is present in a second differential pressure region (23) in the measurement channel (19) and the differential pressure in the second differential pressure region (23) encompasses the differential pressure in the first differential pressure region (22);
• d. transmitting the detected differential pressures to an evaluation unit (120);
• e. determining a flow rate in the measurement channel (19) with the evaluation unit (120) on the basis of the detected differential pressures.