| 摘要 |
PURPOSE: To provide a throwaway dustproof mask which which has an exhaust valve small in dynamic leak-rate, excellent in operability, low in exhaust resistance, and besides low in cost. CONSTITUTION: An exhaust valve is installed at the face the whole of which consists of dust filtering member. The exhaust valve is composed of a flexible disclike valve body 14, a seat 13, which has a support 13b projecting from a base part 13a and supporting the center of the valve body 14 and a circular projection 13c for airtightness contacting with the rim of the valve body and the projection 13c for airtightness of which is in the shape of warping up in circular form in the direction L2 of a second diameter orthogonal to the direction L1 of a first diameter, with its direction L1 of the first diameter as a trough, and a valve cover 15 which has a oblong valve presser 15b for pressing the valve body in the vicinity of the support along the trough of the projection 13c for airtightness and whose rim is locked to the base part of the valve seat 13. |
