| 摘要 |
<p>A breathing apparatus includes: supply means for supplying a breathable gas at a fist super-atmospheric pressure, face-piece means which can be worn by a user, the face-piece means being connected to the supply means and including an exhalation valve and a positive pressure demand valve for establishing a second super-atmospheric pressure, lower than said first super-atmospheric pressure, within the face-piece means when worn by the user, and a flow control device for controlling the flow of gas from the supply means to the face-piece means, the flow control device having a first operating position in which the flow gas to the demand valve is restricted and a second operating position in which the flow of gas to the demand valve is substantially unrestricted, and the flow control device being biased towards its first operating position and being moved to its second operating position by the establishment of the second super-atmospheric pressure within the face-piece means.</p> |
