Abstract: The respiratory protective device minimizes dead space by locating the exhalation valve mechanism slightly spaced from, but directly in front of the mouth. The inhalation valve mechanism surrounds the streamlined flow path leading to the exhalation valve mechanism. The inhalation valve mechanism is located in a common chamber which receives filtered air from all filter assemblies. A chin support is provided which relieves any force to the gums and teeth as a result of the mouthpiece. Alternatively, a mechanism for forcing the wearer's lips closed around the mouthpiece to maintain a seal thereto is provided.

Abstract: A mask for filtering dust and other particulates from air to be breathed by a person and a process for making same. The mask includes a compressible strip covered partially by a sealing material around the entire contact path between the mask and the person's face. The compressible strip provides for changes in the configuration of the face, while the impermeable material maintains a seal during all such changes. Another embodiment includes a support for said compressible strip either in the form of a semi-rigid frame member behind said strip or a plurality of inwardly cantilevered bendable finger members.

Abstract: The alarm system of the present invention includes a pressurized air source for the purpose of pressurizing a face mask which surrounds the mouthpiece of respirator apparatus. An alarm indicating device is installed in the air line between the pressurized air source and the face mask. If the face mask is leaking air to outside the space enclosed by it, the alarm will indicate a continuous flow. If there is leakage from the space enclosed by the face mask into the mouthpiece, the alarm will indicate intermittent leakage since the placement of air will flow only during inhalation. The wearer of the apparatus may thus be confident that either no leakage is occurring or that there is leakage and that appropriate corrective measures should be taken.