| 摘要 |
<p>Improvements in and Relating to Respirators The present invention relates to a filtering facepiece and is concerned with an improvement in the filtering facepiece described in Canadian Patent Application No. 349,880. The filtering facepiece is made from flexible filtering sheet material in the form of a flat pocket 1 which has the general shape of a section of a frustocone with a closed end 2 and an open edge 4. The pocket has side walls 5, 6 which in use overlie the nose of the wearer and underlie the chin of the wearer respectively. At the closed end of the pocket 1 fold lines 11, 12 are provided to define a quadrilateral surface which is folded to extend inwardly of the pocket to strengthen the pocket against collapse against the face of the wearer on inhalation. The quadrilateral surface comprises two triangular surfaces 7 having a common base 8 and apieces e, f opposite the base which lie on the closed end edge of the pocket but inwardly of the corner e', f' of the closed end.</p> |
