Functions provided

Measurement of flows and pulmonary volumes of the patient.

The pneumotachograph is connected to a differential pressure sensor located on the electronic card. This one will transform the analogical signal into numerical data. These data are treated by the software loaded in the electronic card then treated and displayed in the software of the PC.

In order to eliminate moisture from the expired air, the pneumotachograph is heated by an independent power supply and its temperature is controlled by a probe placed in the middle of coiling. It is controlled by the electronic card of the spirometer.
The pneumotachograph is dismountable to allow its cleaning and its decontamination.

Narrative description

The principle of the pneumotachograph is based on the law of POISEUILLE according to which, in streamline flow, through a grid, the flow is proportional to the pressure loss per unit of length. The continuous recording of this pressure loss, i.e. the difference in pressure between two points of the tube, gives a differential curve whose ordinates represent the velocity of air stream, therefore volume per unit of time. In an air stream, the measurement of the fall of pressure remains delicate by the birth of a turbulent flow. However the direct proportionality between speed and difference in pressure is assured only in the absence of swirls. The pressure tap is thus distributed on all the circumference of this one in order to minimize the turbulent effects. Moreover, the selected sensor is used in its linear range.

Diagram

Two flexible pipes leave the pneumotachograph and are connected to the differential pressure sensor of the electronic card of the spirometer.