| 摘要 |
A respirator 10 comprising a hood for enclosing at least the face area of a user, a filter 28, a fan 26 for generating a flow of air through the filter 28, a duct 24 for delivering the flow of filtered air to the vicinity of the user's face, a bypass conduit 44 for abstracting a portion of the flow from the duct 24 and subsequently returning the abstracted portion to the remainder of the flow, means for measuring the flow rate of air through the bypass conduit 44, and means for controlling the fan 26 in response to the measured flow rate. |
