Closed circuit type respirator

摘要

A closed-circuit type respirator includes an oxygen enriching valve provided in an exhalation system of the respirator, preferably at the lower front end of a respirator mask. This oxygen enriching valve comprises a housing having a passage communicating to the exhalation system and a passage communicating to the atmosphere, a first valve which is provided in the passage communicating to the exhalation system and opens only when pressurized for exhalation and a second valve which is provided in the passage communicating to the atmosphere and is opened for a desired period of time by an external force such as manual operation so that the space inside the housing communicates with the atmosphere. By manually or otherwise opening the second valve of the oxygen enriching valve whenever necessary and making a few deep breathings, the exhaled air is discharged in the atmosphere, reducing the pressure in the circulation system and effecting automatic supply of oxygen, whereby insufficiency of oxygen supply can be avoided.