Fig. 1

Complete bench test set-up. Schematic representation of the bench with two test lungs placed in a environmental chamber and the ventilatory circuit consisting of the ventilator, the heated humidifiers and, depending of the chosen configuration, an expiratory valve (valve circuit) or an intentional leak (vented circuit). An unintentionale leak can also be created before test lungs. Hygrometric measurement sites: 1 = Hygrometer measuring ambient conditions around the ventilator; 2 = Hygrometer with high humidity level probe (heated probe); 3 = Second hygrometer