Patent attributes
An underwater breathing device, such as a snorkel, may include an exhalation valve. The exhalation valve is configured to produce positive end-expiratory pressure in the airway of a user of the underwater breathing device in order to reduce the overall work of underwater breathing. The exhalation valve includes a plate defining an exhalation port. The exhalation valve also includes a flexible membrane that is sealable against a surface of the plate and is sized and positioned to be capable of sealing the exhalation port. The flexible membrane is configured to have a sealed position in which the flexible membrane seals the exhalation port such that substantially no exhaled air escapes the snorkel. The flexible membrane is also configured to have an unsealed position in which exhaled air escapes the snorkel.
