Regulator Shut-off

[MikeFerrara]

The problem is there is no garantee the lever won't move. And even if it doesn't there is no garantee that it will never free flow with a purge. Moving the reg all the way to the "surface" position gives the best insurance against free flow. Moving the lever all the way to the "dive" position gives the best breathing. It isn't complicated. If you look at a chart of breathing presures the presure only drops slightly neg for a small portion of the inhalation. When shallow you can leave the lever all the way to the "surface" position and maybe notice little difference. When deeper of in high demand situation you will notice it more. We only use the extreme positions of the lever. Using an intermediate position won't hurt anything other that the reg will be more likely to free flow than with the lever all the way to the "surface" position.

This is how I use the regs and with no trouble or ill effect regardless of the fact that Genesis says I don't.

 

[MikeFerrara]

Genesis once bubbled...
isn't how you are actually setting your regs.

Yes it is.

 

[yknot]

Mike- What's the purpose and proper use then of second adjustment knob? I have been using these turned all the way out so far.

 

[Norm]

IMO: A shutoff is often a desired item for extreme coldwater diving. Many divers making serious dives in arctic conditions prefer some sort of shut off device, but as Genesis points out - IF the first stage is the culprit, the other second stage must act like an overpressure valve to vent off the excess pressure. If it's in your mouth this can cause some creative breathing techniques. I am familiar with the device you mention. Many divers in Europe prefer such a device for that very reason.
Often, a frozen/freeflowing second stage can be shut off momentarily, giving it time to quickly thaw, allowing it to be reused again, (provided freeze up was the culprit). The Zeagle ZX seconds have knobs, (as do many other brands), which can usually be used to throttle or shut flow down. I assume you had an Envoy second or an integrated octopus, without the knob? Many regs use a knob to control flow. The Zeagle knob will do this in the extreme postion, but they actually tend to control the second stage's balance as well. (They aren't there merely to throttle flow as on some regs) The sensitivity switch on the Zeagle second stage is there for a reason. If you keep your octopus, for instance, in the predive position, it really helps to prevent unwanted freeflow, but if you forget to switch it, it will still give you air at any depth. I recently intentionally went to 150' with mine in the predive postion and it required very little extra effort during inhalation, (due to the balanced second stage). Perhaps your's just needs a slight adjustment, although I would have the I.P. checked as well.
Norm