| 摘要 |
A respirator that comprises a head piece (1) that is shaped to form a breathing zone (13) around at least the nose and mouth of the wearer, and an air flow passage (15, 34) for supplying a forced flow of air to the breathing zone. The air flow passage has a constricted portion (46) that includes a flow detecting orifice (52). The forced flow of air generates suction at the flow-detecting orifice. A pressure-responsive indicator device (30) is in fluid communication with the flow-detecting orifice through a tube (54) and is operable to alert the wearer if the suction generated by the air flow through the passage falls below a predetermined value.
|
