Abstract: A respirator exhalation unit (10) comprises a negative pressure valve (120) and a selectively actuable positive pressure valve assembly (130). The position of the positive pressure valve assembly (130) is selectively adjustable to convert the exhalation unit (10) for use in multiple operating modes, such as a negative pressure mode, a powered air mode, and a self-contained breathing apparatus mode (SCBA). Additionally, a closed circuit breathing apparatus (CCBA) adapter assembly (200) can be attached to the exhalation unit for conversion to a CCBA operating mode. Further, the negative pressure valve (120) divides the interior of the exhalation unit into two chambers, one of which functions as a dead space that protects the user from exposure to any harmful contaminants at the end of exhalation.

Abstract: A modular powered air purifying respirator (PAPR) which is comprised of a fan, motor, scroll, and power source mounted within one housing, and which accepts either traditional or conformal filters. Ambient air is drawn into the PAPR module through the attached filter by a fan, which is driven by direct connection to a motor. The pressurized air is then accelerated by an optimized scroll to the outlet in the PAPR housing. The PAPR module can be employed in multiple use configurations. The PAPR module further comprises a removable battery pack module that is easily retained to/removed from the PAPR module, enabling a user to be able to quickly remove a spent battery pack module and install a fresh battery pack module, thereby replacing the batteries within one breath cycle.

Abstract: A respirator mask has a removably mounted support frame that adjustably and removably mounts a corrective lens frame. The corrective lens frame further has a molded bridge with a biasing member embedded therein. A pivotal tab on the support frame is received in one of a plurality of detents on the lens frame for releasably securing the lens frame in the desired position on the support frame. Laterally disposed mounting lugs on the support frame are received in integrally molded pockets in the respirator mask.

Abstract: A gas mask filter canister of varying shapes is filled by orienting the a fill opening to face upwardly, introducing into the fill opening a particulate filter material, and vibrating the filter canister at a frequency and amplitude, and for a time until a predetermined packing density is reached. The invention can be used to fill elliptical or other odd shaped filter canisters having a concave profiles to conform closely to the curvature of the wearer's face.

Abstract: A filter for a gas mask has an elliptical or circular, convex shape to conform to the curvature of the wearer's face, or a planar shape. The filter comprises a double particulate filter element and a double adsorption filter element configured for axial airflow therethrough with a bifurcated flow pattern. The adsorption filter element comprises a granulated charcoal, a composite material having carbon particles combined with binder particles, or an immobilized bed of charcoal granules and EVA-coated fibers.

Abstract: A respirator speech transmitter and exhalation valve module comprising a resilient exhalation valve having a low airflow resistance for exhalation but providing a secure seal against inadvertent inhalation through the exhalation valve module. An exhalation airflow channel is formed between a module body on the outside of the channel and a conical airflow guide and the exhalation valve on the inside of the channel. The exhalation airflow channel is in the form of an amplification horn. The airflow channel produces a smooth airflow for unrestricted exhalation and high intelligibility of a user's speech. The module includes a drinking conduit for selectively fluidly connecting a mouthpiece in the respirator to a beverage container and further includes an electrical communication block with internal and external fittings for connecting a microphone in the mask to a radio or amplifier carried by the mask user.

Abstract: A filter canister assembly for a gas mask comprising a primary canister with a first filter medium adapted to remove aerosols, particulate materials and droplets from air and a second filter medium comprising an adsorbent filter medium adapted to remove toxic gases and arranged in serial communication with the first filter medium in the first canister. A supplementary filter canister has a third filter media adapted to intercept toxic industrial materials and is removably mounted to a first end of the first housing to supplement the ability of the primary filter canister to filter toxic industrial gases.

Abstract: A gas mask having a filter canister mount including an inhalation valve and a self-sealing mechanism that prevents air inflow when a filter canister is removed from the canister mount. In one embodiment, the self-sealing valve includes an elastomeric diaphragm mounted in the inlet port and includes a hinge and a skirt, the skirt having a sealing surface that is biased into contact with a valve seat. The filter canister includes a projection adapted to act on the hinge to pivot the skirt away from the sealing surface as the canister is fitted to the canister mount. In one embodiment, the canister comprises a stacked-radial-flow arrangement of particulate and carbon filtration media. In one embodiment, the gas mask includes a visor having a pair of spaced optical panels with a hinge mounted therebetween for relative rotational movement.