The emergency oxygen supply for passengers in an aircraft comprises an oxygen source with a number of pulse breathing masks which are conductively connected to the oxygen source, wherein an individual shut-off valve which in the non-actuated condition is switched to block is provided in each conduit to a breathing mask. The emergency oxygen supply moreover comprises an impulse breathing control for actuating each individual shut-off valve, as well as an auxiliary conduit which connects the oxygen source to the breathing masks whilst bypassing the individual shut-off valves and which in each case via a check valve is connected to the respective conduit which leads to the breathing mask, or to the breathing mask itself. The auxiliary conduit is connected to the oxygen source via a central shut-off valve which is switched to open in the non-actuated condition.

A bypass knob for a pressure regulator configured for use with a facemask of a breathing apparatus has a first member having a first engagement surface and a second member having a second engagement surface positioned opposite the first engagement surface. At least one slot is formed on the first engagement surface and at least one deflectable beam having a latch is formed on the second engagement surface of the second member. When the first member is rotated in a first direction about the longitudinal axis via a first rotational torque, the latch of the at least one deflectable beam is engaged with the at least one slot to rotate the second member with the first member, and disengaged when the first member is rotated in the first direction via a second rotational torque higher than the first rotational torque.

A bypass knob for a pressure regulator configured for use with a facemask of a breathing apparatus has a first member having a first engagement surface and a second member having a second engagement surface positioned opposite the first engagement surface. At least one slot is formed on the first engagement surface and at least one deflectable beam having a latch is formed on the second engagement surface of the second member. When the first member is rotated in a first direction about the longitudinal axis via a first rotational torque, the latch of the at least one deflectable beam is engaged with the at least one slot to rotate the second member with the first member, and disengaged when the first member is rotated in the first direction via a second rotational torque higher than the first rotational torque.

An air delivery hose (10) has a CBRN resistant outer butyl rubber layer (12) convolute over a metal wire reinforced thermoplastic polyurethane inner hose (14). A combination unit respirator (20) has an air delivery hose (10, 10) with a proximal end (22) with a three position lockable switch (40) that allows selection of APR, PAPR or SCBA modes, and a distal end (24) with a compact demand valve (30) responsive to the switch position. A filter cover accessory (60) is a modular accessory to a PAPR manifold that protects a PAPR filter (62) from premature degradation in harsh environments.

An air delivery hose (10) has a CBRN resistant outer butyl rubber layer (12) convolute over a metal wire reinforced thermoplastic polyurethane inner hose (14). A combination unit respirator (20) has an air delivery hose (10, 10) with a proximal end (22) with a three position lockable switch (40) that allows selection of APR, PAPR or SCBA modes, and a distal end (24) with a compact demand valve (30) responsive to the switch position. A filter cover accessory (60) is a modular accessory to a PAPR manifold that protects a PAPR filter (62) from premature degradation in harsh environments.

A portable communication system includes a remote speaker microphone (RSM) accessory (102) coupled to a portable radio and further coupled to a secondary audio accessory (SAA) (108). The RSM accessory (102) includes a user interface toggle switch (120) that toggles between a first mode of operation and a second mode of operation. Toggling to the first mode of operation selectively routes receive audio from the portable radio to a speaker (112) of the RSM accessory, while generating and routing a periodic audio artifact from the RSM to the SAA (108) for play out at a speaker (316) of the secondary accessory. The received audio is played out of the RSM speaker (112) in parallel with the periodic audio artifact being played out of the secondary accessory speaker (316).

An airflow control valve (20) for use in a breathing apparatus (10) to control a flow of air from a pressurized air supply to a respirator. The valve comprises an inlet port (31) for connection to a pressurized air supply, and first (32) and second (33) outlets. The valve is configurable between a first position in which the inlet port is in restricted fluid communication with the first outlet to allow a restricted flow of air from the inlet port to the first outlet and in which the second outlet is sealed from the inlet port and, a second position in which the inlet port is in substantially unrestricted fluid communication with the second outlet to allow an unrestricted flow of air from the inlet port to the second outlet.

An airflow control valve (20) for use in a breathing apparatus (10) to control a flow of air from a pressurized air supply to a respirator. The valve comprises an inlet port (31) for connection to a pressurized air supply, and first (32) and second (33) outlets. The valve is configurable between a first position in which the inlet port is in restricted fluid communication with the first outlet to allow a restricted flow of air from the inlet port to the first outlet and in which the second outlet is sealed from the inlet port and, a second position in which the inlet port is in substantially unrestricted fluid communication with the second outlet to allow an unrestricted flow of air from the inlet port to the second outlet.

Apparatus and associated methods relate to fitting a virtual mask to a virtual face by first fitting a chin region of the virtual mask to the virtual face, then determining an virtual mask angle that maintains the fitted chin region while simultaneously fitting a nose-bridge region of the virtual mask to the virtual face, and then calculating a fit-quality metric corresponding to the fitted position. In an illustrative embodiment, the fitted chin region may include the high curvature menton region of the chin. In some examples, a virtual mask may be virtually pressed toward the virtual face using a predetermined force corresponding to a force of a mask securing device of a real mask corresponding to the virtual mask In an exemplary embodiment, the fitting of a virtual mask to a virtual face may advantageously yield a mask's fit quality in a brief amount of time.

Apparatus and associated methods relate to fitting a virtual mask to a virtual face by first fitting a chin region of the virtual mask to the virtual face, then determining an virtual mask angle that maintains the fitted chin region while simultaneously fitting a nose-bridge region of the virtual mask to the virtual face, and then calculating a fit-quality metric corresponding to the fitted position. In an illustrative embodiment, the fitted chin region may include the high curvature menton region of the chin. In some examples, a virtual mask may be virtually pressed toward the virtual face using a predetermined force corresponding to a force of a mask securing device of a real mask corresponding to the virtual mask In an exemplary embodiment, the fitting of a virtual mask to a virtual face may advantageously yield a mask's fit quality in a brief amount of time.