Azimuth Rebreather Exhaust Valve

Anyone who knows anything about SCC rebreathers knows that one of the most important adjustments to make is that of the exhaust valve. Too tight and the counterlungs are filled like overstuffed sausages, and exhalation effort is high. Too loose and the rebreather will vent every exhaled breath and you can use up gas in a real hurry. Most manufacturers just tell you to adjust it for satisfactory operation, and leave you to go figure it out yourself. Not Azimuth. They include an industrial quality gauge and have you actually adjust the exhaust valve by measurement. That's a neat solution. You can begin a dive knowing that the rig is set up correctly, and not need to spend a whole dive with the exhaust valve needing adjustment.

Here's the position of the exhaust valve on the back of the hinged lid. This photo is oriented looking down at the bottom of the rig, what is nearest the camera is towards the divers head. That outer ring is the lock ring, and the slotted adjustment is the spring adjustment.

Here's the inside view of the valve. Gas is ported from a Tee where the exhaust hose enters the rig, just before the exhaust counterlung, and is run to the valve through the clear plastic tube shown. This tube flexes as the lid is closed. To prevent collapse, the tube has an internal stainless-steel spring.

To adjust the valve, the diver removes a small plug and attaches the furnished gauge. The gas it turned on, the counterlungs inflated, and then the valve adjusted to the correct opening pressure. No guesswork here.

This is a short area: Hey, how much can there be to an adjustable exhaust valve? The real point is the detail associated with providing a scientific way to adjust the valve the first time, with no trial and error. Nice, eh?