FILTER MASK FOR FACE

摘要

PROBLEM TO BE SOLVED: To provide a face mask which is minimized in pressure drop during the expiration discharge. SOLUTION: An exhaust valve 14 of the filter mask for faces is provided with a flexible flap 24. When the exhaust valve 14 is at a closure position, the flexible flap 24 contacts a curved seal ridge 30 of a valve seat 26. The concave curving of the seal ridge 30 coincides with a deformation curve given by the flexible flap 24 which has one end thereof fixed as done a cantilever while a fixed force and/or a force at least equal to the mass of the free part of the flexible flap 24 is applied on the free part of the flexible flap 24. The flexible flap 24 has a closing force sufficient to apply almost an even pressure on the seal ridge 30.