Abstract: A positive pressure test apparatus for fit testing a facepiece respirator having an exhalation valve, including a cover portion having a central bore with an inwardly directed shoulder at the base. A plunger is provided having a stem, a button portion on one end and a flange portion on the opposite end. The stem is situated within the central bore, the button portion extending above the surface of the cover portion in a rest position, and the flange portion extending below the inwardly directed shoulder. Bias means are located in engagement with the button portion and the shoulder for biasing the plunger from the rest position to a depressed position, wherein the button is flush with the surface of the cover portion and the flange portion seals the exhalation valve. A mounting means is provided to attach the positive pressure test apparatus to the respirator.

Abstract: A snap-on filter for chemical cartridges is presented which includes a filter element comprising a perforated fiberglass prefilter bonded to a felt filter. The filter element is contained within a filter housing which snaps onto the chemical cartridge of a standard gas mask. The fiberglass prefilter is perforated to provide a passage way for fumes into the interior of the filter as well as the filter surface. The perforations increase the overall surface area of the prefilter for filtration. This feature enhances the efficiency and overall life of the filter element.

Abstract: A multiple ply, fold-flat, disposable respirator having, as one ply, a layer of a toxic gas or vapor absorbing material. Another ply is an aerosol filter. The respirator has an inturned vertical seam covered with a strip of foamed elastomer.

Abstract: This invention relates to a dual reusable filter respirator system. The respirator can be worn in dust, mist and fume environments for very long periods of time, while providing increased visibility, safety and comfort for the respirator wearer. A significant feature of the respirator is a pair of triangular shaped filter housings which allow the area of the filter media to be increased while at the same time reducing filter housing obstructions to the vision of the respirator wearer and creating a greater overall compactness of design.