Aqualung ABS octo orientation during air sharing OR design conception

E-mailed the Technical Support department at Aqualung for an answer...

Regarding: the ABS Octo orientation...

Comments/Questions: (below)

My question is regarding the orientation of the ABS octo during air sharing. While I know you can't provide a training related answers, I'm hoping you can provide me a technical one on this unit.

While I understand that the unit can be placed in the mouth in any "orientation" (diaphragm up or down), most often regs are designed for a particular orientation. In this reg, when the diaphragm is facing up, any air inside of the unit would help to keep the diaphragm from pushing on the demand lever inside and reduce the risk of free-flow. If the diaphragm is facing down, the air would be pulling on the diaphragm, therefore pulling against the demand lever inside and be at greater risk of free-flow.

When considering a traditional octopus and the diaphragm facing away from the diver's mouth, this is not an issue even if placed in the mouth upside down outside of the fact that one's nose might be in the way of because of the exhaust deflector on the bottom of those units. Interestingly, most know there is a change in breathing effort if one is inverted in the water with those regs... so, orientation can effect breathing effort. 

I understand that the factory settings and further adjustments from technicians would place the "cracking effort" to draw hard enough to reduce the chance of free-flow, but this would technically not be following factory guidelines. The recipient would be on their way to the surface and even an unbalanced reg will breathe easier.

I also realize that in an out of air situation, cracking effort is the least of anyone's worry, however, the breathing effort set to a comfortable amount is also possible with this unit but it is seldom done.

The only regs I know of that actually can be in any orientation is the Oceanic Omega, the Mares MV, and the Poseidons (pictures attached)..

I'm wondering if there is any data on the intentions of the engineers that created the ABS and if an orientation was ever in mind. I guess this would apply to the Apeks Egress, but as a balanced reg, I didn't consider it in this discussion...

Thanks,

--carlos

Please add your responses or opinions in the comments. Thank you!