| 摘要 |
A breathing apparatus includes a regulator which delivers air to a user wearing a mask. The regulator is connected to the mask through an adaptor. The adaptor includes an exhalation valve which enables the user's breath to pass out of the adaptor to atmosphere. The regulator includes a sensing diaphragm that is movable responsive to pressure in the mask. A main valve delivers air to the mask responsive to opening of a pilot valve. The pilot valve includes a pilot opening. A lever moves in response to the sensing diaphragm to open the pilot opening which causes flow through the main valve. Air from the main valve is also delivered to a positive pressure chamber. Pressure in the positive pressure chamber moves a positive pressure diaphragm which causes a positive pressure spring to biasingly engage the sensing diaphragm. The biasing of the sensing diaphragm causes the regulator to maintain a positive pressure in the mask. Positive pressure is discontinued by relieving pressure form the positive pressure chamber by manually actuating a vent valve. |
