There is disclosed a first stage pressure reducer for a breathing apparatus comprising: a body defining a cavity, the cavity having a higher-pressure region configured to receive higher-pressure gas from a gas source, a lower-pressure region configured to receive lower-pressure gas from the higher-pressure region, and a piston bore, the piston bore connecting the higher-pressure region and the lower-pressure region; a piston configured to move reciprocally through the piston bore, and further configured to transfer gas from the higher-pressure region to the lower-pressure region; a bushing disposed coaxially with the piston bore and around at least a portion of the piston, the bushing arranged to engage the piston and inhibit contact between the piston and the piston bore; and a sealing element arranged between the higher-pressure region and the bushing, the sealing element configured to isolate the bushing from the higher-pressure region. Also disclosed is a self-contained breathing apparatus comprising a first stage pressure reducer.

A first reducing stage of two-stage regulators includes a first chamber that receives a high pressure breathable gas, a second chamber for the breathable gas at an intermediate pressure, and a pressure reducing valve that connects the first and the second chamber. The valve includes a valve seat with an opening for communication between the first and the second chamber, and a plug cooperating with the valve seat and movable between closed and open positions and vice versa. The plug, dynamically connected to a sensor exposed to the outer pressure, includes a transmission mechanism of the mechanical stress due to the outer pressure on the plug, which has a member that stops and starts the kinematic transmission chain according to the mechanical stress due to the outer pressure. Such member includes mechanical stress sensors that stop the kinematic transmission chain when the mechanical stress is below a predetermined threshold value and that restart the kinematic transmission chain when the mechanical stress is equal or above the threshold value.

In variants, a wearable stimulant alert system for a diver can include an air tank, first stage regulator, air hose, second stage regulator, a mouthpiece, a stimulant mechanism, and/or an optional controller. The stimulant mechanism can include a stimulant, stimulant container, and a stimulant release mechanism. The wearable stimulant alert system can function to alert a diver when a stimulant condition (e.g., when the air tank pressure falls below a threshold value) is met.

An integrated manifold system combines in a single, compact, unitary assembly a one-piece, machined manifold for connecting air supply cylinders with a first stage regulator and recharge port. The manifold body has at least one bottle port configured to removably receive a bottle of pressurized air, a first stage regulator chamber, a quick disconnect fitting port, an air channel in fluid communication with the at least one bottle port and the first stage regulator chamber, and an outlet channel in fluid communication with the first stage regulator chamber.

A head-mounted device includes goggles and an image projection module. The image projection module includes a housing fixed on the goggles, an optical element, a projector fixed on the housing and a reflective element disposed within the housing. The housing defines a channel and first and second channel openings. The projector is configured to project an image light beam toward the optical element located in the channel through first and second optical surfaces of the optical element sequentially. The reflective element is configured to receive the image light beam and reflect the received image light beam to generate a reflected light beam directed to the second optical surface. The optical element is configured to refract the reflected light beam toward a lens of the goggles to generate a refracted light beam leaving the channel from the first channel opening and passing through the lens for forming an image.