US Patent 10328293 Breathing equipment training

A breathing equipment training device and a method for breathing training using a breathing equipment training device. The breathing equipment training device includes a shell and a diaphragm. The shell includes a first opening and a second opening, the first opening configured to be inserted into a breathing opening in a mask to form a connection with the breathing opening of the mask, and the second opening configured to be exposed to ambient air. The diaphragm is positioned in an inner cavity of the shell about the second opening, and configured to impede airflow into the shell through the second opening and to traverse along an axis between the first and second openings.