Abstract: Breathing apparatuses which utilize active scrubbing in a closed loop system providing for scrubbing of air on exhalation, but inhalation to be from a clean air source without the air from that source passing back through an active filter immediately prior to inhalation. The systems and methods may also use endothermic reactions from repressurization of make-up air to cool the clean air source providing further comfort.

Abstract: Time delay apparatus for providing a firing action at the end of a predetermined time-delay period. It is used with a source of fluid under pressure, and defines a fluid-receiving chamber for accumulating the fluid when released from the source. A flow controller is connected between the source and the fluid-receiving chamber for providing fluid communication between the source and the fluid-receiving chamber. A triggering assembly initiates flow of fluid from the source through the flow controller and into the fluid-receiving chamber. A piston-form firing pin in the fluid-receiving chamber is actuated by shear pin release for movement to an actuating position for desired firing action when a predetermined pressure has accumulated in the fluid-receiving chamber at the end of the predetermined time-delay period.

Abstract: A batch process produces unitary grains of propellant material. A constituent mixture of the material is prepared by mixing constituents while heating to at least a predetermined pouring temperature within a permissible temperature range. The constituent mixture is poured into a mold, while vibrating it to avoid voids or interfaces within the material, to cast a block of propellant. The cast block is cured for a predetermined period resulting in a cured, cast block of semirigid yet plasticly deformable material. A hydraulic press with a ram carrying a tubular cutting die is positioned, as by transferring the mold without its bottom to the press bed, for permitting grains to be cut by movement of the press ram by forcing the cutting die into the cast block to cut from the block a grain of the propellant material, then extracting the grain for further use. The cutting cycle is repeated until the cast block has yielded a satisfactory number of grains.