A second stage scuba regulator is provided which includes inlet for receiving a supply of compressed air and a piston valve in communication with the inlet for causing air flow through the regulator when the piston valve is opened. A lever is provided for opening and closing of the piston valve, and an air volume controller is provided, which is independently operable from the lever for varying the amount of air flow through the regulator when the piston valve is opened by the lever.

An improved pressure regulator (60) is provided with an eductive flow to maintain the outlet pressure at increased flows through the regulator. The improved regulator broadly includes a body (61) provided with a bore. A valve seat (24) is movably mounted in the bore to provide a valve seat. A valve member (68) is mounted in the body bore for controlled movement toward and away from the seat to vary the area of a main orifice through which fluid is adapted to flow from an inlet to an outlet. The body has a sensing passage (73) communicating a portion (76) of the bore with the exit passage (65). The facing surfaces (74, 76) of the bore and valve member are so dimensioned and configured as to provide an elongated open-ended annular space (78) therebetween that extends along the guide passage from its communicative intersection with the exit passage to a point beyond which the sensing passage communicates with the guide passage. A projection (81) extends from one of the facing surfaces toward the other of the facing surfaces at a location between the open end of the guide passage and the sensing passage to provide a secondary flow restriction. The magnitude of the outlet pressure at increased flows from the inlet to the outlet is better maintained.

A demand valve for a respirator. A fixed tube directs pressurized air flow from the source into an opening for a mask. The venturi effect caused by directed air flow through the housing acts to draw the diaphragm toward the respirator face mask. A portion of the air directed by the tube escapes and is directed over the tube by a hinged three sided arm. Air flow so directed by the arm creates a low pressure area within the arm thus pulling the arm toward the tube. The arm is in engagement with the stem of an air valve which when the arm is drawn toward the tube opens the valve to provide continued air flow into the mask without continued effort on the user's behalf.

Conformal filter cartridges, filtering apparatus using the conformal filter cartridges, and methods of manufacturing the conformal filter cartridges are disclosed. The conformal filter cartridges may include a bed of filter material between a pair of support plates, wherein the major surfaces of the support plates facing the bed of filter material are each curved about at least one axis. The curvature imparted by the support plates provides the conformal configuration to the filter cartridge. The bed of filter material may be loose particulate filter material that may be retained under residual compression between the support plates within the filter cartridge.

A personal respiratory protection device 10 that comprises a mask body 12 that has a structure 35 located on it for receiving a clean air supply source such as a filter cartridge 14. The clean air receiving structure 35 has a first threaded portion 34. The clean air supply source has a second threaded portion 58 that has a thread 60 that mates with a thread 36 of the first threaded portion 34. The first and second threaded portions 34 and 58 engage each other at a high thread pitch and include an integral detente. A stop prevents over-rotation of the clean air supply source 14 relative to the mask body 12 during the securement operation. The inventive device allows the clean air supply source 14 to be attached to the mask body 12 with minimal rotation and is sufficiently intuitive that users may only need one hand to attach and replace the clean air source component 14 without having to remove the respirator 10 from their face.