Sorry for the bad Shakespeare pun.
With the introduction of the DBE and now the Kraken, I though I would start a discussion on whether or not mouthpiece valve are needed on “modern“ DH regs. Are they better left out, kept in or some combination of both ? I know the modern valves are very good and add little to the breathing resistance but still it adds some. Thinking it though and doing some simple testing, I have come to the conclusion that keeping the supply side valve in and removing the exhaust is my preference. My "logic" is this, on the supply side I have the ability to adjust the breathing resistance and vary the venturi so I can compensate for the little bit of resistance it adds. In addition, the valve helps prevent water from getting into the hose and back into the reg. As I measure breathing resistance on the bench, the exhaust is somewhat higher than the supply so anything I can do to reduce it is a plus. Granted, I am talking about small improvements, not major gains.
I see 3 advantages to keeping valves in the exhaust side, one is in the unlikely event of a DBE, exhaust valve or hose failure, it will at least keep most of the water from getting back into the mouthpiece, the other is it does help when there is some water in the exhaust hose that is being a nuisance and lastly, it does keep some water out of the exhaust hose when you have the mouthpiece out of your mouth. With the common use of octos on “modernized” DH regs, the failure of an exhaust valve or hose is not as big of an issue as it once was and once cleared, water from having the mouthpiece out is not an issue so I see those as small benefits compared to the improvement in breathing resistance with it out. .
SO, the question is, are those advantages worth the increase in exhaust resistance, all be it slight? . What do you guys think ? Am I missing something important?